Detecting conflicts between multiple different encoded signals within imagery, using only a subset of available image data, and robustness checks

ABSTRACT

This disclosure relates to advanced signal processing technology including signal encoding and digital watermarking. Image areas are selected in an encoded digital design, and corresponding areas from a printed version of the encoded digital design are evaluated to determined signal robustness after printing. One claim recites an image processing method for selecting image areas to test for robustness of encoded signals, the method comprising: obtaining digital artwork comprising a plurality of colors, the digital artwork comprising multiple instances of an encoded signal; selecting a set encoding tiles, and for each encoding tile determining encoding detectability measure associated therewith; creating a bin for each encoding technology used to encode the encoded signal; for each bin, removing any encoding tile having a detectability measure below a predetermined threshold; for each bin, prioritizing remaining encoding tiles; selecting an encoding tile based on the prioritization per bin, and spatially locating the selected encoding tile relative to the digital artwork. Other technology is described in this patent document.

RELATED APPLICATION DATA

The patent application claims the benefit of U.S. Provisional Patent Application No. 62/888,068, filed Aug. 16, 2019. This patent application is a continuation-in-part of U.S. patent application Ser. No. 16/403,440 (issued as U.S. Pat. No. 10,789,438), filed May 3, 2019, which claims the benefit of U.S. Provisional Patent Application No. 62/803,341, filed Feb. 8, 2019. This patent document is generally related to U.S. Pat. Nos. 9,521,291, 9,690,967, 9,716,807, 10,217,182, 10,460,161, and 10,657,636. Each of the patent documents mentioned above is hereby incorporated herein by reference in its entirety, including all drawings and any appendices.

TECHNICAL FIELD

This disclosure relates to advanced signal processing technology including steganographic embedding and digital watermarking. This disclosure also provides technology for determining and/or detecting signal robustness associated with machine-readable codes within imagery across multiple color channels using a subset of the imagery.

BACKGROUND AND SUMMARY

Portions of this disclosure are described in terms of, e.g., encoded signals for digital designs, product packaging (sometimes just referred to herein as “packaging” or “package”) and other objects. These encoding techniques can be used, e.g., to alter or transform how color inks are printed on various physical substrates. The alterations or transformations preferably result in a printed design carrying machine readable indicia on a surface of a physical object.

Various forms of signal encoding (or “embedding”) include, e.g., “steganographic encoding” and “digital watermarking.” Digital watermarking is a process for transforming physical or electronic media to embed a machine-readable code (or “auxiliary data”) into the media. In some cases, the media is modified such that the embedded code is obscured yet may be detected through an automated detection process. Digital watermarking is often applied to electronic or physical objects such as printed objects, images, audio signals, and video signals. However, it may also be applied to other types of objects, including, e.g., product packaging, electronics such as circuit boards and CPUs, stickers, logos, product hang tags, line-art, software, multi-dimensional graphics models, and surface textures of such objects.

In this document we use the terms “digital watermark” and “watermark” (and various forms thereof) interchangeably.

Auxiliary data embedding systems typically include two components: an encoder (or embedder) that embeds the auxiliary signal in a host image or object, and a decoder (or detector) that detects and reads the embedded auxiliary signal from the host image or object. The encoder may embed the auxiliary signal by altering or transforming a host image or object to carry the auxiliary data. The detection component analyzes a suspect image, object or signal to detect whether an auxiliary signal is present, and if so, extracts or reads information carried in it.

Several particular digital watermarking and auxiliary data embedding techniques have been developed. The reader is presumed to be familiar with the literature in this field. Particular techniques for embedding and detecting imperceptible digital watermarks are detailed in the assignee's patent documents including International Application No. PCT/US2015/44904, filed Aug. 12, 2015 (published as WO 2016025631 A1) and U.S. Pat. Nos. 7,054,461, 7,286,685, 9,129,277, 9,380,186, 9,635,378, 9,747,656 and 9,819,950. Related technology is detailed in Assignee's U.S. Pat. No. 9,754,341. Each of the patent documents mentioned in this paragraph are hereby incorporated herein by reference in its entirety, including all drawings and any 1.

One aspect of the disclosure is an image processing method comprising: obtaining an image comprising a plurality of color channels; for each color channel of the plurality of color channels, creating a grayscale version of the color channel and creating an inverted greyscale version of the color channel; analyzing the grayscale inverted version and the grayscale non-inverted version to locate image areas including an encoded signal, said analyzing yielding a plurality of image areas; generating one or more detectability measures corresponding to the encoded signal for each of the plurality of image areas; for each color channel selecting only one (1) image area as a validation point based on one or more generated detectability measures for that color channel; and generating information associated with a spatial location of each of the validation points in the image.

The method may further include generating a check sheet including markings identifying the spatial location relative to the image for each of the validation points.

In some cases, encoded signal comprises a synchronization component and a message component, in which the one or more detectability measures comprise a first detectability measure comprising a measure corresponding to synchronization component, and a second measure comprising a measure corresponding to the message component. The message component may comprise a GTIN.

Another aspect of the disclosure includes an image processing method comprising: obtaining an image comprising a plurality of color channels; for each color channel of the plurality of color channels, creating a grayscale version of the color channel and creating an inverted greyscale version of the color channel; establishing a virtual grid for each of the non-inverted versions and the inverted versions; centered at each grid point of the virtual grid, determining whether an image area associated with that grid point includes an encoded signal, said determining yielding a plurality of image areas; for grayscale versions including at least one image area, determining a center of an embedding tile associated with that at least one image area; generating one or more detectability measures corresponding to each embedding; for each color channel selecting one (1) image area as a validation point based on one or more generated detectability measures for that color channel; and generating information associated with a spatial location of each of the validation points in the image.

Still further, another aspect may include an image processing method comprising: obtaining an image comprising a plurality of color channels; for each color channel of the plurality of color channels, locate image areas including an encoded signal, said analyzing yielding a plurality of image areas; generating one or more detectability measures corresponding to the encoded signal for each of the plurality of image areas; for each color channel selecting only one (1) image area as a validation point based on one or more generated detectability measures for that color channel; and generating information associated with a spatial location of each of the validation points in the image.

A mobile device app is also disclosed which allows checking areas of printed objects to determine whether they include code conflicts.

Another aspect of the disclosure is a press check sheet, which identifies areas on packaging or other printed object to scan to determine whether there are code conflicts between color channels used to print the package or object.

Further aspects, features and advantages will become even more apparent with reference to the following detailed description, claims and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

FIGS. 1a and 1b illustrate example watermarked digital images, which are part of a test set.

FIGS. 2a-2e are graphs showing standard deviation for various strength measures.

FIG. 3 is a diagram showing construction of a message signature.

FIG. 4 is a histogram showing a detectability measure (linear reference pattern strength) in terms of detection stage passes.

FIG. 5 is a histogram showing a detectability measure (message strength) in terms of successful watermark message reads.

FIGS. 6a-6d are diagrams showing relationships between detected and predicted detectability measures.

FIG. 7 is a heat map showing predicted watermark detection per area for an embedded digital image.

FIG. 8 is a diagram of an electronic device (e.g., a smartphone, mobile device, tablet, laptop or other electronic device).

FIG. 9A shows a watermarked image.

FIG. 9B show a corresponding robustness map of the watermarked image in FIG. 9A.

FIG. 10 is a greyscale version of the watermark image (FIG. 9A) with 50% opacity overlaid onto a white background.

FIG. 11 is the FIG. 9A watermarked image masked using the robustness map in FIG. 9B.

FIG. 12 shows a robustness image where color indicates higher probability of digital watermarking being read and grey indicates a lower probability of the digital watermarking being read.

FIG. 13 shows the robustness image of FIG. 12 including horizontal and vertical swipe probabilities.

FIG. 14 is a block diagram of a signal encoder for encoding a digital payload signal into an image signal.

FIG. 15 is a block diagram of a compatible signal decoder for extracting the digital payload signal from an image signal.

FIG. 16 is a flow diagram illustrating operations of a signal generator.

FIG. 17 is a diagram illustrating embedding of an auxiliary signal into host image signal.

FIG. 18 is a flow diagram illustrating a method for decoding a payload signal from a host image signal.

FIG. 19A shows an image segmented into blocks for decoder analysis.

FIG. 19B shows the FIG. 19A image including a smaller blocked area for decoder analysis.

FIG. 19C represents the corresponding blocked area from FIG. 19B, including decoded signals per sub-area.

FIG. 19D represents another instance of the corresponding blocked area from FIG. 19B, including decoded signals per sub-area.

FIG. 19E represents the FIG. 19D instance, relative to a 1D barcode comparison.

FIG. 20A shows an image including an area for analysis.

FIG. 20B represents the corresponding area from FIG. 20A, including various different decoded signals in some of the sub-areas.

FIGS. 21A and 21B are block diagrams for code conflict detectors.

FIG. 22 shows a press check sheet identifying areas on packaging to scan to determine whether there are code conflicts between color channels used to print the package.

FIGS. 23A, 23B and 23C are flow diagrams illustrating technology used to determine validation points.

FIGS. 24A-24D are images showing different stages of the FIG. 23A flow diagram.

FIGS. 25A-25H are screen shots of a verifier App running on a handheld device.

FIGS. 26A and 26B are images showing different stages of the FIG. 23C flow diagram.

FIG. 27A is an image showing four different encoding tiles, FIG. 27B is a heatmap of encoding strength of the FIG. 27A image; FIG. 27C is a chart showing the different encoding techniques used in FIG. 27A.

FIG. 28 is a flow diagram for one embodiment of Fidelity Point Selection.

DETAILED DESCRIPTION Introduction

The following detailed description is divided into six (6) general sections. It should be understood from the outset, however, that we expressly contemplate combining subject matter from one such section with one or more of the other sections. Thus, the sections and section headings are provided for the reader's convenience and are not intended to impose restrictions or limitations. The sections include: I. Signal Encoder and Decoder; II. Robustness Masks (maps) and Swipe Metrics; III. Construction of Visual Maps Using Robustness as a Mask; IV. Detecting multiple different codes within imagery; V. Evaluating Encoded Imagery at Predetermined Validation Points to Detect Code Conflicts, and Fidelity Point Selection and Confirmation; and VI. Operating Environments.

I. Signal Encoder and Decoder

Encoder/Decoder

FIG. 14 is a block diagram of a signal encoder for encoding a digital payload signal into an image signal. FIG. 15 is a block diagram of a compatible signal decoder for extracting the digital payload signal from an image signal.

While the signal encoder and decoder may be used for communicating a data channel for many applications, one objective for use in physical objects is robust signal communication through images formed on and captured from these objects. Signal encoders and decoders, like those in the Digimarc Barcode Platform from Digimarc Corporation, communicate auxiliary data in a data carrier within image content. Encoding and decoding is applied digitally, yet the signal survives digital to analog transformation and analog to digital transformation. For example, the encoder generates a modulated digital image that is converted to a rendered form, such as a printed image. The modulated digital image includes the encoded signal prior to rendering. Prior to decoding, a receiving device has or communicates with an imager to capture the modulated signal, convert it to an electric signal, which is digitized and then processed by the FIG. 15 signal decoder.

Inputs to the signal encoder include a host image 220 and auxiliary data payload 222. The objectives of the encoder include encoding a robust signal with desired payload capacity per unit of host signal (e.g., a unit may include the spatial area of a two-dimensional tile within the host signal), while maintaining perceptual quality. In some cases, there may be very little variability or presence of a host signal. In this case, there is little host interference on the one hand, yet little host content in which to mask the presence of the data channel within an image. Some examples include a package design that is devoid of much image variability (e.g., a single, uniform color). See, e.g., U.S. Pat. No. 9,635,378, incorporated herein by reference in its entirety.

The auxiliary data payload 222 includes the variable data information to be conveyed in the data channel, possibly along with other protocol data used to facilitate the communication. The protocol of the auxiliary data encoding scheme comprises the format of the auxiliary data payload, error correction coding schemes, payload modulation methods (such as the carrier signal, spreading sequence, encoded payload scrambling or encryption key), signal structure (including mapping of modulated signal to embedding locations within a tile), error detection in payload (CRC, checksum, etc.), perceptual masking method, host signal insertion function (e.g., how auxiliary data signal is embedded in or otherwise combined with host image signal in a package or label design), and/or synchronization method and signals.

The protocol defines the manner in which the signal is structured and encoded for robustness, perceptual quality and/or data capacity. For a particular application, there may be a single protocol, or more than one protocol, depending on application requirements. Examples of multiple protocols include cases where there are different versions of the channel, different channel types (e.g., several digital watermark layers within a host). Different versions may employ different robustness encoding techniques or different data capacity. Protocol selector module 224 determines the protocol to be used by the encoder for generating a data signal. It may be programmed to employ a particular protocol depending on the input variables, such as user control, application specific parameters, or derivation based on analysis of the host signal.

Perceptual analyzer module 226 analyzes the input host signal to determine parameters for controlling signal generation and embedding, as appropriate. It is not necessary in certain applications, while in others it may be used to select a protocol and/or modify signal generation and embedding operations. For example, when encoding in host color images that will be printed or displayed, the perceptual analyzer 256 is used to ascertain color content and masking capability of the host image. The output of this analysis, along with the rendering method (display or printing device) and rendered output form (e.g., ink and substrate) is used to control auxiliary signal encoding in particular color channels (e.g., one or more channels of process inks, Cyan, Magenta, Yellow, or Black (CMYK) or spot colors), perceptual models, and signal protocols to be used with those channels. Please see, e.g., our work on visibility and color models used in perceptual analysis in our U.S. Pat. Nos. 7,352,878, 9,117,268, 9,380,186, 9,401,001, and 9,449,357, which are each hereby incorporated by reference in its entirety.

The perceptual analyzer module 226 also computes a perceptual model, as appropriate, to be used in controlling the modulation of a data signal onto a data channel within image content as described below.

The signal generator module 228 operates on the auxiliary data and generates a data signal according to the protocol. It may also employ information derived from the host signal, such as that provided by perceptual analyzer module 226, to generate the signal. For example, the selection of data code signal and pattern, the modulation function, and the amount of signal to apply at a given embedding location may be adapted depending on the perceptual analysis, and in particular on the perceptual model and perceptual mask that it generates. Please see below and the incorporated patent documents for additional aspects of this process.

Embedder module 230 takes the data signal and modulates it into an image by combining it with the host image. The operation of combining may be an entirely digital signal processing operation, such as where the data signal modulates the host signal digitally, may be a mixed digital and analog process or may be purely an analog process (e.g., where rendered output images, with some signals being modulated data and others being host image content, such as the various layers of a package design file).

There are a variety of different functions for combining the data and host in digital operations. One approach is to adjust the host signal value as a function of the corresponding data signal value at an embedding location, which is limited or controlled according to the perceptual model and a robustness model for that embedding location. The adjustment may be altering the host image by adding a scaled data signal or multiplying by a scale factor dictated by the data signal value corresponding to the embedding location, with weights or thresholds set on the amount of the adjustment according to the perceptual model, robustness model, and/or available dynamic range. The adjustment may also be altering by setting the modulated host signal to a particular level (e.g., quantization level) or moving it within a range or bin of allowable values that satisfy a perceptual quality or robustness constraint for the encoded data.

As detailed further below, the signal generator 228 produces a data signal with data elements that are mapped to embedding locations in an image tile. These data elements are modulated onto the host image at the embedding locations. A tile may include a pattern of embedding locations. The tile derives its name from the way in which it is repeated in contiguous blocks of a host signal, but it need not be arranged this way. In image-based encoders, we may use tiles in the form of a two-dimensional array (e.g., 128×128, 256×256, 512×512) of embedding locations. The embedding locations correspond to host signal samples at which an encoded signal element is embedded in an embedding domain, such as a spatial domain (e.g., pixels at a spatial resolution), frequency domain (frequency components at a frequency resolution), or some other feature space. We sometimes refer to an embedding location as a bit cell, referring to a unit of data (e.g., an encoded bit or chip element) encoded within a host signal at the location of the cell. Again, please see the documents incorporated herein for more information on variations for particular type of media.

The operation of combining may include one or more iterations of adjustments to optimize the modulated host for perceptual quality or robustness constraints. One approach, for example, is to modulate the host image so that it satisfies a perceptual quality metric as determined by perceptual model (e.g., visibility model) for embedding locations across the signal. Another approach is to modulate the host image so that it satisfies a robustness metric across the signal. Yet another is to modulate the host image according to both the robustness metric and perceptual quality metric derived for each embedding location. The incorporated documents provide examples of these techniques. Below, we highlight a few examples. See, e.g., U.S. Pat. Nos. 9,565,335, 9,449,357, 9,401,001, which are each hereby incorporated by reference in its entirety.

For color images, the perceptual analyzer generates a perceptual model that evaluates visibility of an adjustment to the host by the embedder and sets levels of controls to govern the adjustment (e.g., levels of adjustment per color direction, and per masking region). This may include evaluating the visibility of adjustments of the color at an embedding location (e.g., units of noticeable perceptual difference in color direction in terms of CIE Lab values), Contrast Sensitivity Function (CSF), spatial masking model (e.g., using techniques described by Watson in US Published Patent Application No. US 2006-0165311 A1, which is incorporated by reference herein in its entirety), etc. One way to approach the constraints per embedding location is to combine the data with the host at embedding locations and then analyze the difference between the encoded host with the original. The perceptual model then specifies whether an adjustment is noticeable based on the difference between a visibility threshold function computed for an embedding location and the change due to embedding at that location. The embedder then can change or limit the amount of adjustment per embedding location to satisfy the visibility threshold function. Of course, there are various ways to compute adjustments that satisfy a visibility threshold, with different sequence of operations. See, e.g., our U.S. Pat. Nos. 7,352,878, 9,117,268, 9,380,186, 9,401,001 and 9,449,357, each incorporated herein by reference.

The Embedder also computes a robustness model. The computing of a robustness model may include computing a detection metric for an embedding location or region of locations. The approach is to model how well the decoder will be able to recover the data signal at the location or region. This may include applying one or more decode operations and measurements of the decoded signal to determine how strong or reliable the extracted signal. Reliability and strength may be measured by comparing the extracted signal with the known data signal. Below, we detail several decode operations that are candidates for detection metrics within the embedder. One example is an extraction filter which exploits a differential relationship to recover the data signal in the presence of noise and host signal interference. At this stage of encoding, the host interference is derivable by applying an extraction filter to the modulated host. The extraction filter models data signal extraction from the modulated host and assesses whether the differential relationship needed to extract the data signal reliably is maintained. If not, the modulation of the host is adjusted so that it is.

Detection metrics may be evaluated such as by measuring signal strength as a measure of correlation between the modulated host and variable or fixed data components in regions of the host or measuring strength as a measure of correlation between output of an extraction filter and variable or fixed data components. Depending on the strength measure at a location or region, the embedder changes the amount and location of host signal alteration to improve the correlation measure. These changes may be particularly tailored so as to establish relationships of the data signal within a particular tile, region in a tile or bit cell pattern of the modulated host. To do so, the embedder adjusts bit cells that violate the relationship so that the relationship needed to encode a bit (or M-ary symbol) value is satisfied and the thresholds for perceptibility are satisfied. Where robustness constraints are dominant, the embedder will exceed the perceptibility threshold where necessary to satisfy a desired robustness threshold.

The robustness model may also model distortion expected to be incurred by the modulated host, apply the distortion to the modulated host, and repeat the above process of measuring detection metrics and adjusting the amount of alterations so that the data signal will withstand the distortion. See, e.g., U.S. Pat. Nos. 9,380,186, 9,401,001 and 9,449,357 for image related processing.

This modulated host is then output as an output image signal 232, with a data channel encoded in it. The operation of combining also may occur in the analog realm where the data signal is transformed to a rendered form, such as a layer of ink or coating applied by a commercial press to substrate. Another example is a data signal that is overprinted as a layer of material, engraved in, or etched onto a substrate, where it may be mixed with other signals applied to the substrate by similar or other marking methods. In these cases, the embedder employs a predictive model of distortion and host signal interference and adjusts the data signal strength so that it will be recovered more reliably. The predictive modeling can be executed by a classifier that classifies types of noise sources or classes of host image and adapts signal strength and configuration of the data pattern to be more reliable to the classes of noise sources and host image signals that the encoded data signal is likely to be encounter or be combined with.

The output 232 from the Embedder signal typically incurs various forms of distortion through its distribution or use. For printed objects, this distortion occurs through rendering an image with the encoded signal in the printing process, and subsequent scanning back to a digital image via a camera or like image sensor.

Turning to FIG. 15, the signal decoder receives an encoded host signal 240 and operates on it with one or more processing stages to detect a data signal, synchronize it, and extract data.

The decoder is paired with an input device in which a sensor captures an analog form of the signal and an analog to digital converter converts it to a digital form for digital signal processing. Though aspects of the decoder may be implemented as analog components, e.g., such as preprocessing filters that seek to isolate or amplify the data channel relative to noise, much of the decoder is implemented as digital signal processing modules that implement the signal processing operations within a scanner. As noted, these modules can be implemented as software instructions executed within an image scanner or camera, an FPGA, or ASIC, etc.

The detector 242 is a signal processing module that detects presence of the data channel. The incoming signal is referred to as a suspect host because it may not have a data channel or may be so distorted as to render the data channel undetectable. The detector is in communication with a protocol selector 244 to get the protocols it uses to detect the data channel. It may be configured to detect multiple protocols, either by detecting a protocol in the suspect signal and/or inferring the protocol based on attributes of the host signal or other sensed context information. A portion of the data signal may have the purpose of indicating the protocol of another portion of the data signal. As such, the detector is shown as providing a protocol indicator signal back to the protocol selector 244.

The synchronizer module 246 synchronizes the incoming signal to enable data extraction. Synchronizing includes, for example, determining the distortion to the host signal and compensating for it. This process provides the location and arrangement of encoded data elements within the host signal.

The data extractor module 248 gets this location and arrangement and the corresponding protocol and demodulates a data signal from the host. The location and arrangement provide the locations of encoded data elements. The extractor obtains estimates of the encoded data elements and performs a series of signal decoding operations.

As detailed in examples below and in the incorporated documents, the detector, synchronizer and data extractor may share common operations, and in some cases may be combined. For example, the detector and synchronizer may be combined, as initial detection of a portion of the data signal used for synchronization indicates presence of a candidate data signal, and determination of the synchronization of that candidate data signal provides synchronization parameters that enable the data extractor to apply extraction filters at the correct orientation, scale and start location of a tile. Similarly, data extraction filters used within data extractor may also be used to detect portions of the data signal within the detector or synchronizer modules. The decoder architecture may be designed with a data flow in which common operations are re-used iteratively or may be organized in separate stages in pipelined digital logic circuits so that the host data flows efficiently through the pipeline of digital signal operations with minimal need to move partially processed versions of the host data to and from a shared memory unit, such as a RAM memory.

Signal Generator

FIG. 16 is a flow diagram illustrating operations of a signal generator. Each of the blocks in the diagram depict processing modules that transform the input auxiliary data into a digital payload data signal structure. The input auxiliary data may include, e.g., a Global Trade Item Number (GTIN) developed by GS1. For example, the GTIN may be structured in the GTIN-12 format for UPC codes. Of course, the input auxiliary data may represent other plural bit codes as well. For a given protocol, each block provides one or more processing stage options selected according to the protocol. In processing module 300, the auxiliary data payload is processed to compute error detection bits, e.g., such as a Cyclic Redundancy Check (CRC), Parity, check sum or like error detection message symbols. Additional fixed and variable messages used in identifying the protocol and facilitating detection, such as synchronization signals may be added at this stage or subsequent stages.

Error correction encoding module 302 transforms the message symbols of the digital payload signal into an array of encoded message elements (e.g., binary or M-ary elements) using an error correction method. Examples include block codes, BCH, Reed Solomon, convolutional codes, turbo codes, etc.

Repetition encoding module 304 repeats and concatenates the string of symbols from the prior stage to improve robustness. For example, certain message symbols may be repeated at the same or different rates by mapping them to multiple locations within a unit area of the data channel (e.g., one unit area being a tile of bit cells, as described further below).

Repetition encoding may be removed and replaced entirely with error correction coding. For example, rather than applying convolutional encoding (⅓ rate) followed by repetition (repeat three times), these two can be replaced by convolution encoding to produce a coded payload with approximately the same length.

Next, carrier modulation module 306 takes message elements of the previous stage and modulates them onto corresponding carrier signals. For example, a carrier might be an array of pseudorandom signal elements, with equal number of positive and negative elements (e.g., 16, 32, 64 elements), or other waveform. We elaborate further on signal configurations below.

Mapping module 308 maps signal elements of each modulated carrier signal to locations within the channel. In the case where a digital host signal is provided, the locations correspond to embedding locations within the host signal. The embedding locations may be in one or more coordinate system domains in which the host signal is represented within a memory of the signal encoder. The locations may correspond to regions in a spatial domain, temporal domain, frequency domain, or some other transform domain. Stated another way, the locations may correspond to a vector of host signal features, which are modulated to encode a data signal within the features.

Mapping module 308 also maps a synchronization signal to embedding locations within the host signal, for embodiments employing an explicit synchronization signal. An explicit synchronization signal is described further below.

To accurately recover the payload, the decoder extracts estimates of the coded bits at the embedding locations within each tile. This requires the decoder to synchronize the image under analysis to determine the embedding locations. For images, where the embedding locations are arranged in two dimensional blocks within a tile, the synchronizer determines rotation, scale and translation (origin) of each tile. This may also involve approximating the geometric distortion of the tile by an affine transformation that maps the embedded signal back to its original embedding locations.

To facilitate synchronization, the auxiliary signal may include an explicit or implicit synchronization signal. An explicit synchronization signal is an auxiliary signal separate from the encoded payload that is embedded with the encoded payload, e.g., within the same tile). An implicit synchronization signal is a signal formed with the encoded payload, giving it structure that facilitates geometric/temporal synchronization. Examples of explicit and implicit synchronization signals are provided in our previously cited U.S. Pat. Nos. 6,614,914, and 5,862,260, which are each hereby incorporated herein by reference in their entirety.

In particular, one example of an explicit synchronization signal is a signal comprised of a set of sine waves, with pseudo-random phase, which appear as peaks in the Fourier domain of the suspect signal. See, e.g., U.S. Pat. Nos. 6,614,914, and 5,862,260, describing use of a synchronization signal in conjunction with a robust data signal. Also see U.S. Pat. No. 7,986,807, which is hereby incorporated by reference in its entirety.

Our US Patent Application Publication No. US 2012-0078989 A1, which is hereby incorporated by reference in its entirety, provides additional methods for detecting an embedded signal with this type of structure and recovering rotation, scale and translation from these methods.

Examples of implicit synchronization signals, and their use, are provided in U.S. Pat. Nos. 5,862,260, 6,614,914, 6,625,297, 7,072,490 and 9,747,656, which are hereby incorporated by reference in their entirety.

Signal Embedding in Host

FIG. 17 is a diagram illustrating embedding of an auxiliary signal into host signal. As shown, the inputs are a host signal block (e.g., blocks of a host digital image) (320) and an encoded auxiliary signal (322), which is to be inserted into the signal block. The encoded auxiliary signal may include an explicit synchronization component, or the encoded payload may be formulated to provide an implicit synchronization signal. Processing block 324 is a routine of software instructions or equivalent digital logic configured to insert the mapped signal(s) into the host by adjusting the corresponding host signal sample(s) at an embedding location according to the value of the mapped signal element. For example, the mapped signal is added/subtracted from corresponding a sample value, with scale factor and threshold from the perceptual model or like mask controlling the adjustment amplitude. In implementations with an explicit synchronization signal, the encoded payload and synchronization signals may be combined and then added or added separately with separate mask coefficients to control the signal amplitude independently.

Applying the method of FIG. 16, the product or label identifier (e.g., in GTIN format) and additional flag or flags used by control logic are formatted into a binary sequence, which is encoded and mapped to the embedding locations of a tile. For sake of illustration, we describe an implementation of a tile having 256 by 256 embedding locations, where the embedding locations correspond to spatial domain embedding locations within an image. In particular, the spatial locations correspond to pixel samples at a configurable spatial resolution, such as 100 DPI or 300 DPI. In this example, we will explain the case where the spatial resolution of the embedded signal is 300 DPI, for an embodiment where the resulting image with encode data is printed on a package or label material, such as a paper, plastic or like substrate. The payload is repeated in contiguous tiles each comprised of 256 by 256 of embedding locations. With these embedding parameters, an instance of the payload is encoded in each tile, occupying a block of host image of about 1.28 by 1.28 inches. These parameters are selected to provide a printed version of the image on paper or other substrate. At this size, the tile can be redundantly encoded in several contiguous tiles, providing added robustness. An alternative to achieving desired payload capacity is to encode a portion of the payload in smaller tiles, e.g., 128 by 128, and use a protocol indicator to specify the portion of the payload conveyed in each 128 by 128 tile. Erasure codes may be used to convey different payload components per tile and then assemble the components in the decoder, as discussed in U.S. Pat. No. 9,311,640, which is hereby incorporated herein by reference in its entirety.

Following the construction of the payload, error correction coding is applied to the binary sequence. This implementation applies a convolutional coder at rate ¼, which produces an encoded payload signal of 4096 bits. Each of these bits is modulated onto a binary antipodal, pseudorandom carrier sequence (−1, 1) of length 16, e.g., multiply or XOR the payload bit with the binary equivalent of chip elements in its carrier to yield 4096 modulated carriers, for a signal comprising 65,536 elements. These elements map to the 65,536 embedding locations in each of the 256 by 256 tiles.

An alternative embodiment, for robust encoding on packaging employs tiles of 128 by 128 embedding locations. Through convolutional coding of an input payload at rate ⅓ and subsequent repetition coding, an encoded payload of 1024 bits is generated. Each of these bits is modulated onto a similar carrier sequence of length 16, and the resulting 16,384 signal elements are mapped to the 16,384 embedding locations within the 128 by 128 tile.

There are several alternatives for mapping functions to map the encoded payload to embedding locations. In one, these elements have a pseudorandom mapping to the embedding locations. In another, they are mapped to bit cell patterns of differentially encoded bit cells as described in U.S. Pat. No. 9,747,656. In the latter, the tile size may be increased to accommodate the differential encoding of each encoded bit in a pattern of differential encoded bit cells, where the bit cells corresponding to embedding locations at a target resolution (e.g., 300 DPI).

Our U.S. Pat. No. 9,635,378 describes methods for inserting auxiliary signals in areas of package and label designs that have little host image variability. These methods are particularly useful for labels, including price change labels and fresh food labels. These signal encoding methods may be ported to the printing sub-system in scales used within fresh food, deli and meat departments to encode GTINs and control flags for variable weight items in the image of a label, which is then printed by the printer sub-system (typically a thermal printer) on the label and affixed to an item.

For an explicit synchronization signal, the mapping function maps a discrete digital image of the synchronization signal to the host image block. For example, where the synchronization signal comprises a set of Fourier magnitude peaks or sinusoids with pseudorandom phase, the synchronization signal is generated in the spatial domain in a block size coextensive with the 256 by 256 tile (or other tile size, e.g., 128 by 128) at target embedding resolution.

Various detailed examples of encoding protocols and processing stages of these protocols are provided in our prior work, such as our U.S. Pat. Nos. 6,614,914, 5,862,260, 6,674,876, 9,117,268, and 9,635,378, which are hereby incorporated by reference. More background on signaling protocols, and schemes for managing compatibility among protocols, are provided in U.S. Pat. No. 7,412,072, which is hereby incorporated by reference.

One signaling approach, which is detailed in U.S. Pat. Nos. 6,614,914, and 5,862,260, is to map elements to pseudo-random locations within a channel defined by a domain of a host signal. See, e.g., FIG. 9 of U.S. Pat. No. 6,614,914. In particular, elements of a watermark signal are assigned to pseudo-random embedding locations within an arrangement of sub-blocks within a block (referred to as a “tile”). The elements of this watermark signal correspond to error correction coded bits. These bits are modulated onto a pseudo-random carrier to produce watermark signal elements (block 306 of FIG. 16), which in turn, are assigned to the pseudorandom embedding locations within the sub-blocks (block 308 of FIG. 16). An embedder module modulates this signal onto a host signal by increasing or decreasing host signal values at these locations for each error correction coded bit according to the values of the corresponding elements of the modulated carrier signal for that bit.

FIG. 18 is a flow diagram illustrating a method for decoding a payload signal from a host image signal. Implementations of a watermark decoder and watermark processors available from Digimarc Corporation include:

Digimarc Mobile Software Development Kit; and

Digimarc Embedded Systems SDK.

The Embedded Systems SDK is the one typically integrated into scanner hardware.

Corresponding encoder embodiments available from Digimarc Corporation include:

Digimarc Barcode SDKs

Digimarc Barcode Plugin

Returning to FIG. 18, the frames are captured at a resolution preferably near the resolution at which the auxiliary signal has been encoded within the original image (e.g., 300 DPI, 100 DPI, etc.). An image up-sampling or down-sampling operation may be performed to convert the image frames supplied by the imager to a target resolution for further decoding.

The resulting image blocks supplied to the decoder from these frames may potentially include an image with the payload. At least some number of tiles of encoded signal may be captured within the field of view, if an object with encoded data is being scanned. Otherwise, no encoded tiles will be present. The objective, therefore, is to determine as efficiently as possible whether encoded tiles are present.

In the initial processing of the decoding method, it is advantageous to select frames and blocks within frames that have image content that are most likely to contain the encoded payload. From the image passed to the decoder, the decoder selects image blocks for further analysis. The block size of these blocks is set large enough to span substantially all of a complete tile of encoded payload signal, and preferably a cluster of neighboring tiles. However, because the distance from the camera may vary, the spatial scale of the encoded signal is likely to vary from its scale at the time of encoding. This spatial scale distortion is further addressed in the synchronization process.

For more on block selection, please see U.S. Pat. No. 9,521,291, which is hereby incorporated by reference in its entirety.

Please also see assignee's U.S. Pat. No. 9,922,220, which is hereby incorporated by reference, for more on block selection where processing time is more limited.

The first stage of the decoding process filters the image to prepare it for detection and synchronization of the encoded signal (402). The decoding process sub-divides the image into blocks and selects blocks for further decoding operations. For color images, a first filtering stage converts the input color image signal (e.g., RGB values) to a color channel or channels where the auxiliary signal has been encoded. See, e.g., U.S. Pat. No. 9,117,268, which is hereby incorporated herein by reference in its entirety, for more on color channel encoding and decoding. For an image captured under red illumination by a monochrome scanner, the decoding process operates on this “red” channel sensed by the scanner. Some scanners may pulse LEDs of different color to obtain plural color or spectral samples per pixel as described in our U.S. Pat. No. 9,749,607, which is hereby incorporated by reference.

A second filtering operation isolates the auxiliary signal from the host image. Pre-filtering is adapted for the auxiliary signal encoding format, including the type of synchronization employed. For example, where an explicit synchronization signal is used, pre-filtering is adapted to isolate the explicit synchronization signal for the synchronization process.

In some embodiments, the synchronization signal is a collection of peaks in the Fourier domain. Prior to conversion to the Fourier domain, the image blocks are pre-filtered. See, e.g., LaPlacian pre-filter in U.S. Pat. No. 6,614,914. A window function is applied to the blocks and then a transform to the Fourier domain, applying an FFT. Another filtering operation is performed in the Fourier domain. See, e.g., pre-filtering options in U.S. Pat. Nos. 6,988,202, 6,614,914, and 9,182,778, which are hereby incorporated by reference in their entirety.

For more on filters, also see U.S. Pat. No. 7,076,082, which is hereby incorporated by reference in its entirety. This patent describes a multi-axis filter, e.g., an oct-axis filter. Oct axis compares a discrete image sample with eight neighbors to provide a compare value (e.g., +1 for positive difference, −1 or negative difference), and sums the compare values. Different arrangements of neighbors and weights may be applied to shape the filter according to different functions. Another filter variant is a cross shaped filter, in which a sample of interest is compared with an average of horizontal neighbors and vertical neighbors, which are then similarly summed.

Next, synchronization process (404) is executed on a filtered block to recover the rotation, spatial scale, and translation of the encoded signal tiles. This process may employ a log polar method as detailed in U.S. Pat. No. 6,614,914 or least squares approach of U.S. Pat. No. 9,182,778, to recover rotation and scale of a synchronization signal comprised of peaks in the Fourier domain. To recover translation, the phase correlation method of U.S. Pat. No. 6,614,914 is used, or phase estimation and phase deviation methods of U.S. Pat. No. 9,182,778 are used.

Alternative methods perform synchronization on an implicit synchronization signal, e.g., as detailed U.S. Pat. No. 9,747,656, which is hereby incorporated herein by reference in its entirety.

Next, the decoder steps through the embedding locations in a tile, extracting bit estimates from each location (406). This process applies, for each location, the rotation, scale and translation parameters, to extract a bit estimate from each embedding location (406). In particle, as it visits each embedding location in a tile, it transforms it to a location in the received image based on the affine transform parameters derived in the synchronization, and then samples around each location. It does this process for the embedding location and its neighbors to feed inputs to an extraction filter (e.g., oct-axis or cross shaped). A bit estimate is extracted at each embedding location using filtering operations, e.g., oct axis or cross shaped filter (see above), to compare a sample at embedding locations with neighbors. The output (e.g., 1, −1) of each compare operation is summed to provide an estimate for an embedding location. Each bit estimate at an embedding location corresponds to an element of a modulated carrier signal.

The signal decoder estimates a value of each error correction encoded bit by accumulating the bit estimates from the embedding locations of the carrier signal for that bit (408). For instance, in the encoder embodiment above, error correction encoded bits are modulated over a corresponding carrier signal with 16 elements (e.g., multiplied by or XOR with a binary anti-podal signal). A bit value is demodulated from the estimates extracted from the corresponding embedding locations of these elements. This demodulation operation multiplies the estimate by the carrier signal sign and adds the result. This demodulation provides a soft estimate for each error correction encoded bit.

These soft estimates are input to an error correction decoder to produce the payload signal (410). For a convolutional encoded payload, a Viterbi decoder is used to produce the payload signal, including the checksum or CRC. For other forms of error correction, a compatible decoder is applied to reconstruct the payload. Examples include block codes, BCH, Reed Solomon, Turbo codes.

Next, the payload is validated by computing the check sum and comparing with the decoded checksum bits (412). The check sum matches the one in the encoder, of course. For the example above, the decoder computes a CRC for a portion of the payload and compares it with the CRC portion in the payload.

At this stage, the payload is stored in shared memory of the decoder process. The recognition unit in which the decoder process resides returns it to the controller via its interface. This may be accomplished by various communication schemes, such as IPC, shared memory within a process, DMA, etc.

II. Robustness Masks (Maps) and Swipe Metrics

One problem with digital watermarking product packages and other physical objects is obtaining visibility that is subjectively pleasing to a graphic designer and others. For example, a graphic designer may be hesitant to introduce too much “noise” into a product's design. The term “noise” refers to visible artifacts in a spatial domain that may be created when the design is transformed to carry an encoded signal, e.g., steganographic encoding or digital watermarking. These artifacts may sometimes have a noise-like, grainy or other visible appearance. As a result, the designer may crank down digital watermark signal strength (or “gain”) or remove the watermarking from some design areas altogether. This may result in a loss of signal robustness, e.g., embedded watermarks carried in the product package may not be detectable in some or all areas of the package surface. We refer to such a package as a low-gain design. (A low-gain design may include areas without watermarking, areas with low-signal gain, perhaps along with some design areas that are robustly embedded.)

Now imagine such a low-gain design in a retail checkout scenario. For example, please see assignee's U.S. Pat. No. 9,224,184, which is hereby incorporated herein by reference in its entirety. In this setting packages move along at retail checkout, e.g., on a conveyor or with employee-assist. A watermark detector analyzing image data representing a low-gain design may not be able to detect watermarks from the image data. A non-detect may result in a slowed check-out process, requiring human intervention or other process to enter the product's ID code.

Low-gain designs need to be discovered prior to press runs. For example, tens of thousands of packages can be printed (e.g., on offset or digital printing presses) before it's realized that a watermarked package design is a low-gain type. At the printing press stage, it is often too late to “stop the presses” to create new printing plates and roll out a new design, one having a higher encoded signal strength.

Aspects of this disclosure address this problem by predicting embedding strength and/or detectability across a printed product package from the digital design itself. If the predicted strength falls short of a predetermined threshold or other metric the digital design can be re-embedded, flagged for inspection and/or redesigned, etc. A mapping (e.g., a heat map or robustness map representing encoded signal detectability) may be generated to visually indicate predicted watermark readability across the image surface. Moreover, strength across a package's scanning length or swipe path (e.g., horizontal and/or vertical swipe paths) can be quantified and adjusted, if needed.

As discussed above an encoded signal, e.g., digital watermarking, may include multiple components. For example, digital watermarking may include a synchronization component (e.g., a reference pattern) and a message (or payload) component. These components may be combined in some domain (e.g., transform domain) to form a watermark signal. In some cases, the synchronization component is introduced into a host signal (e.g., an image or audio signal) prior to introduction of the message component.

The synchronization component can be utilized during signal detection. An embedded host signal undergoes various transformations, such as conversion to and from an analog domain (e.g., offset or digital printing and then image capture of the printed design). Using parameters from a watermark embedder (e.g., the reference pattern), a watermark detector may perform a series of correlations or other operations on captured imagery to detect the presence of a digital watermark. If it finds a watermark, it may determine its orientation within the host signal.

Using the orientation, if necessary, the watermark detector may extract or decode the message. Some implementations do not perform correlation, but instead, use some other detection process or proceed directly to extract the watermark signal.

Watermark detectors can be designed in many ways. One design utilizes stages, where a synchronization component is evaluated in a first stage and if it meets certain thresholds (e.g., based on correlation with a reference pattern) it passes onto a second stage. The message component can be evaluated and read in the second stage. Of course, additional stages can be added, e.g., pre-filtering stages and various strength check stages.

There are many types of synchronization components that may be used with the present technology.

For example, a synchronization signal may be comprised of elements that form a circle in a particular domain, such as the spatial image domain, the spatial frequency domain, or some other transform domain. Assignee's U.S. Pat. No. 7,986,807, which is hereby incorporated herein by reference in its entirety, considers a case, e.g., where the elements are impulse or delta functions in the Fourier magnitude domain. The reference signal comprises impulse functions located at points on a circle centered at the origin of the Fourier transform magnitude. These create or correspond to frequency peaks. The points are randomly scattered along the circle, while preserving conjugate symmetry of the Fourier transform. The magnitudes of the points are determined by visibility and detection considerations. To obscure these points in the spatial domain and facilitate detection, they have known pseudorandom phase with respect to each other. The pseudorandom phase is designed to minimize visibility in the spatial domain. In this circle reference pattern example, the definition of the reference pattern only specifies that the points should lie on a circle in the Fourier magnitude domain. The choice of the radius of the circle and the distribution of the points along the circle can be application specific. For example, in applications dealing with high resolution images, the radius can be chosen to be large such that points are in higher frequencies and visibility in the spatial domain is low. For a typical application, the radius could be in the mid-frequency range to achieve a balance between visibility requirements and signal-to-noise ratio considerations.

Another example is found in Assignee's U.S. Pat. No. 6,614,914, which is hereby incorporated herein by reference in its entirety. There, a synchronization component (or “orientation pattern”) can be comprised of a pattern of quad symmetric impulse functions in the spatial frequency domain. These create or correspond to frequency peaks. In the spatial domain, these impulse functions may look like cosine waves. An example of an orientation pattern is depicted in FIGS. 10 and 11 of the '914 patent.

Another type of synchronization component may include a so-called Frequency Shift Keying (FSK) signal. For example, in Assignee's U.S. Pat. No. 6,625,297, which is hereby incorporated herein by reference in its entirety, a watermarking method converts a watermark message component into a self-orienting watermark signal and embeds the watermark signal in a host signal (e.g., imagery, including still images and video). The spectral properties of the FSK watermark signal facilitate its detection, even in applications where the watermarked signal is corrupted. In particular, a watermark message (perhaps including CRC bits) can be error corrected, and then spread spectrum modulated (e.g., spreading the raw bits into a number of chips) over a pseudorandom carrier signal by, e.g., taking the XOR of the bit value with each value in the pseudorandom carrier. Next, an FSK modulator may convert the spread spectrum signal into an FSK signal. For example, the FSK modulator may use 2-FSK with continuous phase: a first frequency represents a zero; and a second frequency represents a one. The FSK modulated signal is can be applied to rows and columns of a host image. Each binary value in the input signal corresponds to a contiguous string of at least two samples in a row or column of the host image. Each of the two frequencies, therefore, is at most half the sampling rate of the image. For example, the higher frequency may be set at half the sampling rate, and the lower frequency may be half the higher frequency.

When FSK signaling is applied to the rows and columns, the FFT magnitude of pure cosine waves at the signaling frequencies produces grid points or peaks along the vertical and horizontal axes in a two-dimensional frequency spectrum. If different signaling frequencies are used for the rows and columns, these grid points will fall at different distances from the origin. These grid points, therefore, may form a detection pattern that helps identify the rotation angle of the watermark in a suspect signal. Also, if an image has been rotated or scaled, the FFT of this image will have a different frequency spectrum than the original image.

For detection, a watermark detector transforms the host imagery to another domain (e.g., a spatial frequency domain), and then performs a series of correlation or other detection operations. The correlation operations match the reference pattern with the target image data to detect the presence of the watermark and its orientation parameters.

Yet another synchronization component is described in assignee's U.S. Pat. No. 7,046,819, which is hereby incorporated by reference in its entirety. There, a reference signal with coefficients of a desired magnitude is provided in an encoded domain. These coefficients initially have zero phase. The reference signal is transformed from the encoded domain to the first transform domain to recreate the magnitudes in the first transform domain. Selected coefficients may act as carriers of a multi-bit message. For example, is an element in the multi-bit message (or an encoded, spread version of such) is a binary 1, a watermark embedder creates a peak at the corresponding coefficient location in the encoded domain. Otherwise, the embedder makes no peak at the corresponding coefficient location. Some of the coefficients may always be set to a binary 1 to assist in detecting the reference signal. Next, the embedder may assign a pseudorandom phase to the magnitudes of the coefficients of the reference signal in the first transform domain. The phase of each coefficient can be generated by using a key number as a seed to a pseudorandom number generator, which in turn produces a phase value. Alternatively, the pseudorandom phase values may be computed by modulating a PN sequence with an N-bit binary message. With the magnitude and phase of the reference signal defined in the first transform domain, the embedder may transform the reference signal from the first domain to the perceptual domain, which for images, is the spatial domain. Finally, the embedder transforms the host image according to the reference signal.

A correlation-based technique can be used to help locate and decode the watermark signal.

To evaluate watermark characteristics in a digital design and use such to predict detectability on a corresponding printed object, we generate detectability measures that correspond in various ways to the embedded watermark signal (e.g., the synchronization component and/or the message component). The premise is that if we can estimate the detectability measures in a digital design, then we can estimate the chance of a successful read when that digital design is printed, e.g., on a product package, scanned (e.g., image capture of the printed product package) and decoded.

Some of our detectability measures are described and applied below.

For this analysis we used 300 digital test images each including a 2 by 2 inch patch. The image size and sample size of these images is not critical but is useful to help illustrate aspects of this disclosure. Two examples of test image patches are shown in FIG. 1a and FIG. 1 b.

Each of the digital test images is embedded with digital watermarking including a reference pattern and a message. Some of the images include so-called “sparse” digital watermarking, e.g., as described in assignee's U.S. Pat. No. 9,635,378, which is hereby incorporated herein by reference in its entirety. Some images include digital watermarking as generally discussed, e.g., in assignee's U.S. Pat. No. 9,380,186, which is hereby incorporated herein by reference in its entirety.

These embedded, test images are then printed, e.g., using an Epson 4900 printer with a GRACoL profile and semi-matte paper. An image capture device, e.g., the Datalogic 9800i (including a horizontal and vertical camera) with a video feed enabled was used to capture 100 digital images of each printed test image for each camera (so a total of 200 digital images or “scans” were captured for each test image). The printed images were each positioned in a way that allows maximum detection for the given camera. Additionally, each printed image was placed on a plate (again, in the most readable position on the scanner) and automatically swiped 400 times in front of each camera. A robotic arm (“robot”) that moves the printed images in front of the cameras was used for this other image capture. All captured, digital images were saved and evaluated as discussed below.

A watermark detector analyzed each digital image captured from the scans. The following detection measures were determined.

Reference Pattern Strength (RPS): For each captured digital image we determined its RPS, which, e.g., comprises a sum of bounded frequency domain signal peak strengths. This value can be normalized, e.g., between 0 and 2, for each peak strength. RPS mean from the test images are shown in FIG. 2a , which has a rather large standard deviation.

Linear Reference Pattern Strength (LRPS): Here we determine the average of unbounded peak strengths. For example, we compare each reference pattern peak to its neighbors (e.g., 4, 6 or 8 neighbors). In other words, how does this peak compare to its neighborhood, e.g., in terms of magnitude or other measure. The subject peak value can be divided by the average value of its neighbors. Its measure includes a better behaved standard deviation compared to the RPS, as seen in FIG. 2 b.

Phase Deviation Strength (PDS): This measure represents how consistent is the phase of reference pattern peaks are relative to translation. It is, however, very sensitive to how well rotation and scale are estimated, which leads to extremely high standard deviation, as shown in FIG. 2 c.

Criterion Strength (CS): Is a combination of Reference Pattern Strength and Phase Deviation. The value of Criterion Strength can be represented as: Criterion Strength=0.17*RPS−PDS−46.5.

However, since this criterion includes two measures with high variance, as seen in FIG. 2d , it is difficult to estimate the CS.

Message Strength (MS): One example of message “strength” was described in assignee's U.S. Pat. No. 7,286,685, which is hereby incorporated by reference in its entirety. From the '685 patent, one approach for measuring strength of a message signal is as follows: 1. Use the message payload read from the watermark to re-create the original embedded bit sequence (including redundantly encoded bits from error correction coding) used for the watermark. 2. Convert the original bit sequence so that a zero is represented by −1 and a one is represented by 1. 3. Multiply (element-wise) the soft-valued bit sequence used to decode the watermark by the sequence of step 2. 4. Create one or more measures of watermark strength from the sequence resulting in the previous step. One such measure is the sum of the squares of the values in the sequence. Another measure is the square of the sum of the values in the sequence. Other measurements are possible as well. For example, soft bits associated with high frequency components of the watermark signal may be analyzed to get a strength measure attributed to high frequency components. Such high frequencies are likely to be more sensitive to degradation due to photocopying, digital to analog and analog to digital conversion, scanning and re-printing, etc. 5. Compare the strength measures to thresholds . . . .

Another method, introduced in this patent document, is a correlation metric based on a watermark's message signature. With reference to FIG. 3, a signature is generated based on a payload or message, e.g., carrying a GTIN, UPC, identifier or some other plural-bit message. While there are specific bit numbers illustrated in FIG. 3, the present disclosure is not so limited, as we may include many more or less bits for the various payload components. The payload can be combined with CRC bits, and the combination can be error corrected, e.g., with a convolutional encoder. A payload header can be added to help distinguish the type or format of the watermarking or to indicate a payload version. The resulting bit string can be used as the signature.

Each bit of the signature can be placed redundantly in a digital image. For example, in a tile design, where watermark tiles (e.g., a 128×128 message tile) are tiled across an image or image area, each bit of the signature can be mapped, e.g., 8-16 times, to a pseudo-random location (with pseudo-random sign) to create a message tile.

The signature is unique for each GTIN and the Message Strength (MS) and can be represented as a relationship between the embedded signature and the sign of the decoded signature:

${MS} = {\sum\limits_{i = 1}^{1024}\;{{{EmbeddedSignature}(i)}*{{sign}\left( {{DecodedSignature}(i)} \right)}}}$

This measure has relatively small standard deviation, as seen in FIG. 2 e.

Additional signal strength metrics are discussed in U.S. Pat. No. 7,054,461, e.g., a so-called Power Ratio and Payload Recovery Assessment. The U.S. Pat. No. 7,054,461 patent is hereby incorporated herein by reference in its entirety.

The power ratio metric measures, e.g., the degradation of a watermark signal (e.g., a synchronization component) at selected frequencies.

The Payload Recovery Assessment measures watermark strength, including the degree of correlation between a synchronization component and a detected signal, and a measure of symbol errors in raw message estimates. One way to measure the symbol errors is to reconstruct the raw message sequence using the same error correction coding process of the embedder on the valid message extracted from the watermark. This process yields, for example, a string of 1000 binary symbols, which can be compared with the binary symbols estimated at the output of a spread spectrum demodulator. The stronger the agreement between the reconstructed and detected message, the stronger the watermark signal.

Thanks to their small variance leading to easier predictability, Linear Reference Pattern Strength (LRPS) and the Message Strength (MS) are selected in a first example as detectability measures. These measures are first correlated with an actual watermark detector behavior. For example, LPRS is correlated with passing stage 1 (or “first stage”) of a detection process. Here, as mentioned above, stage 1 includes a synchronization stage, where a reference pattern can be detected or correlated relative to a known reference pattern. FIG. 4 shows a histogram of LRPS values based on whether a watermark tile passed the first stage. The blue lines indicate scanned images having an LRPS that passed the first stage, and the red lines indicate scanned images having an LRPS that did not pass the first stage. A decision can be made to establish a threshold (vertical dashed line) indicating that the first stage threshold is passed if the LRPS is larger than a predetermined LRPS value. While this threshold need not be held completely, however, it greatly simplifies the criteria. For example, purposes we set a strength threshold, T, of 1.27, so T_(LRPS)=1.27. Of course, the threshold can be moved up, e.g., 1.5 to ensure less false positives, or moved down, e.g., 1.1 if more false positives are acceptable.

FIG. 5 shows a histogram plot for Message Strength. Again, the blue lines represent those images with a certain Message Strength resulting in successful message reads, and the red lines represent those images with a certain Message Strength resulting in unsuccessful message reads. A strength threshold (vertical dashed line in FIG. 5) can be determined to represent when a watermark message is read. For example, purposes we set of strength threshold, T, of 280 so T_(MS)=280. This value can change to accommodate more or less false positive tolerance.

Using this criteria for LRPS and MS, we can predict that a digital watermark is likely to be successfully read when:

1. LPRS>T_(LPRS); and

2. MS>T_(MS).

This is all fine and good for data that has been collected in a “design-print-image capture-detect” scenario. But, recall that we are interested in predicting how a digital image, once embedded with digital watermarking and before printing, will be detectable after printing. So how do we apply our above thresholds and detectability measures to a digital image, one that once watermarked will be used to guide printing, e.g., on physical product packaging?

One approach is to transform watermarked digital images so that the transformed, watermarked images correspond to what an image capture device sees, and to what a watermark detector ultimately analyzes when detecting a watermark from captured imagery. In a transformed, watermarked image case, we can extract the LRPS and MS statistics using a watermark detector on the transformed, watermarked digital image. Using these detectability measures and the thresholds discussed earlier, we can predict whether a digital watermark will be read once printed on a physical surface. We affectionately call these types of transformations an “attack,” because they degrade the quality of a watermarked digital image.

One improvement is that the whole image pipeline (digital image→watermark embedding→print→color transform (e.g., with a red LED/laser)→image capture→watermark detect) need not be simulated during the attack. Rather, we introduce an attack that would make the LGS and MS statistics generally correspond to the statistics extracted directly from a scanned image.

For example, if we want to estimate robustness using a specific scanner, we can evaluate the attack by comparing the LRPS and MS determined on “attacked” watermarked digital images with the LRPS and MS obtained by printing the images, putting them in front of the scanner and taking image captures from the scanner (e.g., Datalogic's 9800i) for watermark detection.

One example attack for watermarked embedded digital images proceeds as follows. (While this example is geared toward a two-camera system like the Datalogic 9800i, it need not be so.)

-   -   a. Add noise to the original digital artwork. Gaussian noise is         one example. For a two-camera system, noise standard deviation         for the vertical camera is approximately 28, and for horizontal         camera is approximately 22.     -   b. For the horizontal camera, blur the digital image. This         simulates a 30-50 degree pre-distortion and resampling. A 7×7         averaging kernel can be used for the blur.     -   c. Down sample the image in a manner similar to watermark         detection. For example, if a watermark detector down samples by         3, then the image can be convolved with a 3×3 averaging kernel         and subsampling.     -   d. For multiple in-plane (yaw) rotations obtain detectability         measures.

Our initial watermarked, digital image test set was degraded according to the above attack. Referring to FIGS. 6a-6d , results from the images on x axis is the measures extracted from “attacked” digital images. On y axis is the measures extracted from printed/scanned captures of the same (but not attacked) embedded digital. The “x” marks correspond to the so-called “sparse” watermarking mentioned above, and the “+” marks correspond to watermarking introduces through changes in process colors, e.g., as discussed in assignee's U.S. Pat. No. 9,380,186. Ideally, we want the values to be correlated, therefore, as close to diagonal as possible. FIGS. 6a and 6b show closely correlated values.

With reference to FIG. 6c and FIG. 6d , examples of wrong fits includes the “+” markers on the bottom of the horizontal camera attacks. We found that these data points correspond to very dark images which are unreadable using our test scanner. Thus, the simulated detectability measures are much higher than the captured ones. This is a result of our test scanner, and not of the attack.

Given a digital watermarked image, we can now attack it to obtain estimated LRPS and MS detectability measures. For example, after an attack, a digital watermark detector analyzes the attacked image and determines detection measures, e.g., on a per tile basis, throughout the image. We can simplify a detection prediction by saying that LRPS and MS measure must be larger than some threshold in order to detect. This can be written in probabilistic form as: P(detection)=P(LRPS>T _(LRPS))·P(MS>T _(MS))

For simplification, and letting LRPS=LGS (just a different name) we can assume that the estimation error of LGS and MS follow a normal distribution

with zero mean and standard deviation measured from the plots above, σ_(LGS)=0.3,σ_(MS)=100 Finally, the probability of detection can be written as:

P(,) = P(lgs > T_(LGS); lgs ∼ 𝒩(, σ_(LGS)²)) ⋅ P(ms > T_(MS); ms ∼ 𝒩(σ_(MS)²)) = (1 − cdf(1.27;, 0.3²)) ⋅ (1 − cdf(280;, 100²))

With knowledge of the robot arm speed, the test image size and the watermark tile configuration, we can simulate a swipe path moving through the watermark tiles. By doing multiple simulations with different swipe starting locations, we can obtain the average swipe rate. Swipe rate is determined since printed product packages are often “swiped” in front of a camera during retail check out. So, the camera (and watermark detector) sees a swath of imagery or a stripe of imagery across a package.

Probability of swipe detection using local read rates P(

,

) from frame f of swipe s:

${P\left( {{swipe}\mspace{14mu} s} \right)} = {1 - {\prod\limits_{{frames}\mspace{14mu} f\mspace{14mu}{in}\mspace{14mu}{swipe}\mspace{14mu} z}\;\left( {1 - {P(,)}} \right)}}$

Final swipe detection rate is computed as an average over all (or a subset of all) simulated swipes s along a path, e.g., horizontal or vertical path or for an entire image.

With reference to FIG. 7, after attack and watermark detection per tile or area, a heat map can be generated showing the overall probability of watermark detection for the image. That is, probabilities can be assigned color values, and the color values are shown in a spatial map form relative to the image. In FIG. 7, red areas are those having a low-gain or low probability of watermark detection once the digital image (watermarked, but without the attack) is printed, scanned and analyzed with a watermark detector. The blue areas are those having a high chance of detection from the printed digital image (watermarked, but without the attack). The scale moves through other colors between red and blue.

FIG. 7 also includes a horizontal and vertical color bar. The vertical bar shows swipe read probability if a swipe path is taken horizontally through the image. For example, at a particular location, the vertical color bar corresponds to a virtual swipe along the horizontal dashed line. (As discussed above, the probability of tiles along the path can be averaged to determine the overall path probability. Alternatively, extreme probabilities can be weighted or discounted depending on tolerances for a particular application.) Here, along the horizontal dashed path, its light blue, indicating a likely read. The horizontal color bar also shows the collective probability for a vertical swipe path (e.g., along the dashed vertical line). An overall score can be determined for the digital image (e.g., “63%” shown in the lower right-hand corner of FIG. 7). A threshold can be set, e.g., somewhere between 60-90% (e.g., below 90%, or below 85%, or below 80%, or below 75%, or below 70% or below 65%, etc.) and any image falling below such threshold will be flagged for or automatically re-embedded, e.g., using a stronger embedding strength or different type of encoding protocol.

One or more graphical user interfaces (GUI) may be configured to control display of the heat map on a display screen, e.g., computer monitor, touchscreen display, smartphone display, OLED display, TV screen, projection, etc. The GUIs may be configurable to allow emphasis of embedded areas that have low-gain or high robustness. In other cases, the GUI allows a user to highlight areas for re-embedding, e.g., on a touchscreen display that a user may trace an area for re-embedding. The GUI keeps track of the trace and corresponds such to the digital image, which can be used as a mask for re-embedding digital watermarking.

III. Construction of Visual Maps Using Robustness as a Mask

A heat map or robustness map (e.g., as shown in FIG. 7) can be used as an image mask to visually evidence digital watermark robustness or detectability throughout an image.

For example, consider the image shown in FIG. 9A. This particular image represents a product package design, e.g., for delicious Tomato Sauce. The illustrated design includes digital watermarking embedded therein. The watermarked design can be analyzed, e.g., as discussed above in Section II, to determine watermark signal detectability.

A robustness map can be generated corresponding to the detectability results. For example, and with reference to FIG. 9B, a robustness map can be generated to show areas having relatively stronger detectability. In this case (unlike FIG. 7), the white areas show those areas having sufficient detectability, e.g., based on a threshold or relative to other image areas having lower detectability (e.g., shown in black color in FIG. 9B). In particular, the white areas may indicate a high probability of the digital watermarking being read by a red LED Point of Sale scanner, whereas dark areas may indicate low probability of the watermark being read by the red LED scanner. Assignee's U.S. Pat. No. 9,380,186, which are both incorporated herein by reference in their entireties, discuss various spectral characteristics of typical red LED scanners.

One illustrative process operates on a watermarked image (e.g., FIG. 9A) and its corresponding robustness map (e.g., 9B). The following steps can be performed in image editing and design suites, e.g., Adobe's Photoshop or Illustrator, etc. Of course, these steps can be automated with software code, scripts, functions, circuitry and/or modules.

1. Convert the original digital watermarked image in FIG. 9A to greyscale.

2. Modify the greyscale image's opacity to some percentage less than 100%, e.g., to between 20% and 95%, to between 40% and 80%, to between 50% and 70 percent, etc.

3. Overlay the modified greyscale image onto a white (or lightly colored) background. (FIG. 10 shows a greyscale version of FIG. 9A with 50% opacity overlaid onto a white background.)

4. Mask the original embedded image using a robustness map indicating the robustness of the digital watermarking at each pixel, groups of pixels or image areas in the original image. FIG. 11 shows a result of the original watermarked image FIG. 9A masked using the FIG. 9B robustness map. The resulting white areas in FIG. 11 correspond to the black areas in FIG. 9B, e.g., those have low or no watermark robustness.

5. Overlay the masked image (e.g., FIG. 11) on top of the modified greyscale image (FIG. 10). FIG. 12 shows the result of this overlaying. This final robustness image (or “signal detection map”) indicates those areas having a high probability of digital watermark detection in original design color and indicates in grey those areas having a low (or relatively lower) probability of the digital watermark detection.

Such a result (e.g., FIG. 12) provides a designer with a practical and visual example of how a package will be machine-read, including a more realistic design presentation compared, e.g., to the FIG. 7 heat map. Thus, this signal detection map (FIG. 12) is helpful to see where the digital watermark is strong (by showing the original design color) and where it is weak (shown in grey or other color); and it also allows inspection of modification artifacts (e.g., signal embedding artifacts) to be assessed directly on signal detection map itself.

In some implementations, we add a swipe component to the FIG. 12 final robustness image. That is, we provide horizontal and vertical swipe information (like in FIG. 7) to allow a designer a fuller picture of how the digital watermarking will be read by a scanner. For example, FIG. 13 shows horizontal (grey result) and vertical (color result) swipe information. The resulting swipe information can, e.g., keep with the final robustness image color scheme (e.g., grey for hard to read areas and original color for detectable areas). Or the resulting swiping information can be a totally different color, e.g., red for stop, no good; and green for good to go, etc.

While we have used specific colors to represent various results (e.g., original color=robustness, grey=no or less robustness) other colors can be used instead. For example, white or black can be used for low/no robustness areas.

IV. Detecting Multiple Different Codes within Imagery

The presence of multiple, different encoded signals (e.g., steganographic codes, barcodes, etc.) in imagery can sometimes create havoc, e.g., in the retail packaging space where a consumer is typically charged according to the presence of a code. Take an easy example of a 2 different 1D barcodes printed on a box of cereal, with the first 1D barcode corresponding to a box of “Sugar O's” and the second 1D barcode corresponding to a box of “Honey Sugar O's”. A consumer at checkout could be charged twice (once for a box of Sugar O's and another for a box of Honey Sugar O's) if both of the 1D barcodes are scanned, even though the consumer only intended to purchase 1 box of cereal. The consumer gets charged twice, and a retail store's inventory management system now has erroneous information.

Now consider some progressively harder examples. In a first case, a box of cereal includes an encoded signal redundantly covering some or a majority of the surface area of a box of cereal. Each instance of the encoded signal carries a payload, e.g., UPC payload 1. Examples of encoded signals may include, e.g., steganographic encoding or digital watermarking, or some other encoding scheme. The cereal box also includes a 1D UPC barcode. The 1D UPC barcode also carries UPC payload 1. No disagreement between the 1D UPC barcode code and the encoded signal code, so the consumer is only charged once. (See, e.g., assignee's U.S. Pat. No. 10,262,176, which is hereby incorporated herein by reference in its entirety, for related solutions for conflicting/similar codes including wait times between decoded codes.)

In a second case, each instance of the encoded signal carries the same payload as above, UPC payload 1. The UPC 1D barcode, however, is different and conveys UPC payload 2. Here, a conflict exists, and a retailer runs the risk of charging a customer twice. Moreover, the conflict between encoded signal and the 1D barcode may indicate a larger problem, e.g., a manufacturing issue such as mislabeling or a wrong product altogether.

In a third case, various different encoded signals are provided on the package, with a first encoded signal including UPC payload 1, and a second encoded signal including UPC payload 2. A conflict results here again.

It's imperative that such conflicts are discovered early in the design process, preferably before printing and distribution.

Let's look at a typical workflow for a product package. For example, a workflow may include one or more of the following steps:

1) Receive digital package files from, e.g., via a secure FTP.

2) Pre-Flight to determine that we have all info. Pre-flight is a term used to describe a preliminary step that evaluates received information, and may include reformatting, decompressing files, and an overall evaluation whether the received digital page files can be assembled into a printable package. Package artwork is typically represented by a collection of files in a variety of different formats e.g., Bitmaps (*.tiff, *psd, etc.), vector imagery (*.ps, *.ai, etc.), and fonts (*.abf, *.ttf, etc.). A final rendered packaged can be “built” using the aforementioned files using a variety of different strategies, from a 1-layer bitmap to numerous layers of vector and bitmap imagery utilizing multiple fonts.

3) Enter Package/Retailer/Printer/Supplier in CRM system, e.g., Microsoft Dynamics CRM (not shown). Optionally, the materials may include an XML file which can be used to automatically enter the information. In this case, a manual check will help ensure accuracy.

4) Assign to Teams. For example, different tasks can be assigned to different workstations, or to available operators. An operator queue can be examined to determine availability.

5) Create an identity file in an identity management system (e.g., housed in the cloud) and associate the GTIN. The creation and management of these services can be accomplished through a web-portal to the identity management system or programmatically through Web APIs. If the packaging materials includes a 1D barcode number, e.g., in a GTIN format, this information can be obtained and provided as used as the encoded signal payload or part of a payload, or to a storage location at which an encoded signal payload will point to.

6) Review Files—Different Classifications. These classifications may include assignment of package embedding difficultly. This may prompt additional resources or billing requirements.

7) Print-out Initial Client Proof.

8) Embed encoded signal.

9) Print Watermarked Proof

10) Test on POS Scanner. This is a preliminary test to see if the proof will read.

11) Assemble Package for Manual Test

12) Manual Test. This can be a detailed process, where each package face is tested, e.g., at different reading angles. For example, each side is tested on a POS scanner with a vertical camera and a horizontal camera. The package is passed over the scanner, e.g., 2, 4 or 8 times per side and then number of reads is recorded. The side is rotated, e.g., 90 degrees and the process is repeated for that side, rotated again and retested, etc. Each package side can be so tested, and the results recorded. A grade can be assigned based on successful reads. Of course, the process is benefited from automation where a package is passed in front of a scanner, e.g., with a robot arm, conveyor belt or some other movement mechanism.

13) Complete QC Checklist

-   -   13a) compare results of digital grade and manual grade; decide         whether to accept or refine embedded package.

14) Send Approved file to Customer or Printer via FTP

15) At the Printer, enter file into system (e.g., ESKO Packaging Management software, provided by ESKO, with offices worldwide including in Miamisburg, Ohio 45342 (USA)).

16) Various ink and printing pre-checks.

17) Ready the file for printing plate manufacture, including allowing the client or pre-press designer a final review (e.g., 1-bit .tif file) review. Approval or change request received.

18) Plate manufacture (e.g., for an offset press) based on the design file.

19) Print run—print the design file.

So how do code conflicts surface? For example, in step 5 an encoded signal preferable duplicates a provided GTIN payload from a 1D barcode.

A few sources of conflicts may include, e.g., operator error (erroneous data entry), using the wrong 1D barcode file, etc. At the printing press stage (e.g., steps 15-19), product design families may be associated in a packaging management system. A product design family may include, e.g., a line of dish soap which includes related designs, with some design elements being identical and others being unique. For example, the background across the family designs may include a design element in a Cyan color channel that doesn't change from family member to family member. Yet, each family member may include other design elements that are unique (e.g., color changes to reflect dish soap fragrance). In this dish soap example, the printer may realize an advantage by reusing the common Cyan element printing plate across the entire family. If the common plate is manufactured based on a first design file, with a first encoded signal represented in the first design file, then each package printed with this plate will include the first encoded signal in the common plate area (e.g., background). But if each family member includes a unique GTIN to represent that it's a different product than the family, and other printing plates are manufactured for these unique design elements and unique GTIN, each family member will also include different encoded signals. So, a package printed with the common Cyan plate (including the 1^(st) encoded signal) and a unique family plate (e.g., including a 2^(nd) encoded signal) will have at least two conflicting codes printed thereon.

If these types of code conflict problems are discovered after printing, the printer or customer may lose tens of thousands of dollars, if not more.

We have developed a “scanner verifier” to help catch such potential code conflicts before printing plate manufacture, or before complete print press runs. Thus, the scanner verifier can be used prior to printing plate manufacture (e.g., just prior to step 18, above) or as the first sheets start rolling off the presses in step 19.

The scanner verifier preferably includes a plurality of code detectors. For example, it may include a signal decoder, e.g., as discussed relative to FIGS. 15 and 18 and a barcode decoder, e.g., a 1D and/or 2D barcode decoder.

Suitable 1D and 2D barcode decoders include, e.g., the open source ZXing (“Zebra Crossing”) barcode project. Of course, other 1D and/or 2D barcode decoders could be used instead. The ZXing barcode decoders support 1D product codes (UPC-A, UPC-E, EAN-8 and EAN-13), 1D industrial codes (e.g., Code 39, Codabar, etc.) and 2D codes (e.g., QR Code, Data Matrix, etc.). The ZXing source code can be obtained at https://github.com/zxing/zxing/releases. The ZXing decoder is configured to accept scanline data. (A scanline includes a row of image data, e.g., pixel values or binarizied versions of the pixel values.) How the scanlines are generated, however, is left to the implementation.

The scanner verifier also preferably includes a code comparator and a display generator.

A scanner verifier is discussed further with reference to FIGS. 21A and 21B, where an image, e.g., from a design file or from a scanner (e.g., a scanned sheet from a print run) is analyzed in parallel (FIG. 21A) or in series (FIG. 21B). A barcode module 501 analyzes the image to determine whether it contains a barcode, and if so, decodes the barcode and provides the barcode's payload (e.g., representing a GTIN number) to a comparator module 504. Barcode module 501 will also determine whether the image includes two or more barcode (e.g., a 1D and a 2D barcode). Each of the barcode's payloads can be provided if found, optionally along with a spatial image location of the barcode(s). The image is also analyzed by a Decoder Module 502 (also called a “Decoder” in this Section IV) to detect and decode encoded signals. For example, the Decoder Module 502 can be configured as a steganographic or watermark decoder. The Decoder Module 502 outputs a decoded code (e.g., representing a GTIN number), optionally along with a spatial image location for each decoded code, to the Comparator Module 504. The Comparator Module 504 compares payloads from both the Barcode Module 501 and the Decoder Module 502, to see if they match and/or whether there are any code conflicts. The Comparator Module 504 can be configured to compare plural codes from each of the Barcode Module 501 (e.g., compare a 1D with a 2D code) and the Decoder Module 502 (e.g., compare a 1^(st) decoded signal and a 2^(nd) decoded signal), and between all codes regardless of decoder source.

The Comparator Module 504 can output the codes and one or more conflict indicators for display or for a report. The conflict indicators can indicate, e.g., no conflict or information regarding the code conflicts.

Results Module 506 can create information for a graphical user interface for display. Different colors, boxing and/or highlighting can be used to show results of the conflict comparison.

Returning to the Barcode Module 501, scanlines are provided from data representing the image for 1D barcode analysis. For example, data representing the image may include a greyscale or binarizied version of the image. Scanline production and management may be controlled by a Barcode Module 501 sub-module or a different module altogether (a “scanline generator module”). The scanlines typically represent 1 or more pixel row(s) of image data. In some cases, we combine adjacent (top and bottom) scanlines together (e.g., with an AND function) to form a single scanline. A scanline's length can vary, e.g., in one implementation the scanlines are 4 inches long. This means that for a 300 dpi image, a single scan line will contain 1200 pixels. In some cases, the scanlines can be overlapped, e.g., 25-75%. For example, a first scanline from a first image row is four inches long and starts at point (0″,0″), with the top left corner of the image being the origin, and ends at (4″,0″). The 2^(nd) scanline starts at (1″, 0″) and runs to (5″, 0″) and so on. If reading a horizontal barcode, the scanline generator module can provide scanlines along the first image pixel row, then skip down the image if no barcode is found. For example, the next scanline may be 10, 20 or 50 rows down the image. The scanline generator module can continue to skip down the image until a barcode is read, or until it reaches the bottom of the image.

If the Barcode Module 501 detects and decodes a barcode from a particular scanline, the scanline generator module preferably provides scanlines from the next n number of rows (n being an integer) below the successfully read scanline. For example, scanlines from the next 3 rows, 5 rows, 10 rows or 20 rows are analyzed to get a read. The Barcode Module 501 can be configured to only output a code if all of the n scanlines (or a predetermined subset of the n scanlines) also generate the same code.

The scanline generator module can also be configured to provide vertical scanlines by using image columns instead of rows. This will help find a barcode that may be rotated at a 90-degree angle within the imagery. Additionally, off-axis (e.g., 45 degree) scanlines can be generated and provided to the Barcode Module 501 for analysis.

Returning to the Decoder Module 502 (also referred to as “Decoder”), the Decoder can be configured to analyze multiple different color separations (or planes) from the image. For example, the image may include Red (R), Green (G), Blue (B) separations or may include Cyan (C), Magenta (M), Yellow (Y), Black (K) separations. The image may also include Spot Color 1 and Spot Color 2, etc. The Decoder can be configured to analyze each of these separations separately looking for encoded signals. In some cases, separations can be combined, perhaps with various weights, to represent, e.g., chrominance (e.g., R−G; or 0.5R−0.5G) or Luminance (e.g., R+G+B; or 0.2126*Rlinear+0.7152*Glinear+0.0722*Blinear, for Luminance (Y linear) in the sRGB specification). The Decoder can then analyze the Chrominance and Luminance channels in search of encoded signals.

In one implementation, the Decoder is configured to analyze image blocks or tiles. With reference to FIG. 19A, an image is segmented into blocks, e.g., 512×512 or 128×128 pixel blocks. (The Decoder may down-sample (or up-sample) the blocks to achieve a native encoded signal resolution. For example, a 512×512 block may be down-sampled to a 128×128 block or tile.) While we prefer to block out the entire image as in FIG. 19A, in some cases only a portion of the image is blocked out (FIG. 19B). These blocks can be used for all separations in the image, e.g., the Yellow separation is blocked in the same manner as the Magenta and Cyan separations, etc. In alternative implementations, each separation or groups of separations are blocked separately.

Each block (or a subset of blocks) from each separation can be analyzed by the Decoder to determine whether that block contains an encoded signal code and, if so, may associate the code with a particular block or image spatial area. For example, the blocks can be numbered, tracked or assigned to a spatial location within the image. The code can be assigned to the numbered, tracked or assigned block from which it was decoded, or otherwise assigned to an image spatial area. For example, and with reference to FIG. 19C, the Decoder operates on blocks from one separation (e.g., Magenta or Chrominance) from the FIG. 19B drawing, and may assign decoded codes to spatially oriented blocks. In all likelihood, the results will be stored in a table or memory structure, along with some spatial indicator. (Of course, the Decoder could operate on all image blocks instead, e.g., as from FIG. 19A.) In this example, an encoded signal (ES1) is detected in the majority of blocks as shown in FIG. 19C. The Decoder did not find an encoded signal in three (3) of the blocks, nos. 8, 17 and 19, so these blocks are illustrated as empty. (The Comparator Module 504 would not find a code conflict in this FIG. 19C separation since all of the decoded codes include the same code ES1, e.g., which may correspond to a GTIN number.)

With reference to FIG. 19D, the Decoder operates on another image FIG. 19B separation (e.g., Cyan or Luminance). An encoded signal (ES1) is detected and decoded in the majority blocks, but a second encoded signal (ES2) is detected and decoded in two (2) blocks, e.g., block nos. 14 and 19. No encoded signal is found in two (2) of the blocks, nos. 8 and 17, and are illustrated as empty. (The Comparator Module 504 would find a code conflict within this separation since two different codes, ES1 and ES2, are decoded. Additionally, the Comparator Module 504 may indicate a conflict between the two separations, the first having an ES1 in block 14, while the second has an ES2 in block 14.) The Decoder can operate in the same manner on all separations and channels associated with the image.

With reference to FIG. 19E, the Comparator Module 504 can be configured to compare each of the decoded codes (e.g., ES1 and ES2, from all separations) with any associated 1D and/or 2D barcode codes. For example, in the illustrated example, a 1D barcode is recognized and decoded by the Barcode Module 501, and the results are provided to the Comparator Module 504. The 1D barcode's code carries the same ES1 code in this example. The Comparator Module 504 notes a conflict in blocks 14 and 19, since those blocks (in various separations) include an ES2 code that is different than the 1D barcode's ES1 code. This conflict can be noted and reported to the Display Module 506.

The Display Module 506 may be configured to provide output such as a “conflict map.” The conflict map may include, e.g., a report, color information, information for spatial display, or highlights for those image areas including a conflict. Display Module 506 output can be provided to a display screen. A conflict map can be shown by boxing or highlighting the relevant image blocks. In some cases, a text overlay is provided in the blocks' relative spatial position in the imagery noting the ES2 code or other text indicating a conflict. In still other cases, the conflict boxes are shown with an opaque overlay, or in gray instead of in color. Non-conflicting blocks, e.g., those blocks corresponding to the 1D barcode's code, can be shown in original image colors, and/or with text overlays (e.g., indicating an “OK” or “√” symbol or text showing the ES1 code). The text overlays can be color-coded to indicate “all clear” (e.g., green) or “conflict” areas (e.g., red).

Now with reference to FIG. 20B, the Display Module 506 may be configured to control display of additional and/or alternative information. The information can be displayed on a display such as a computer monitor, touchscreen display, smart phone screen, TV monitor, etc. The Decoder Module 502 operates on all separations for the image blocks noted in FIG. 20A. In the illustrated example, the Decoder Module 502 decodes two different encoded signal codes, ES3 and ES4. No codes are found in blocks 1, 3, 9, 18 and 19, so these blocks are illustrated as being empty. The ES3 codes are only found in blocks 2, 4, 7 and 12, whereas the ES4 code is found in various other image areas. The Barcode Module 501 determines that the image includes a 1D barcode in block 15 carrying an ES4 code, and a QR code in block 25 carrying a similar but different code relative to the ES4.

The Comparator Module 504 is configured in this example so that conflicts between the 1D barcode (carrying an ES4) and any other codes are flagged. So, a conflict is noted for block nos. 2, 4, 7, 12 and 25. This information can be provided to the Display Module 506, which can create a conflict map, e.g., an overlay of different colors (as in FIG. 20B) for the conflicting areas, perhaps relative to the original image shown in FIG. 20A. Instead of overlaying colors, the respective areas may be displayed or highlighted with a graphic box, highlighting, colored shape or outline. In some cases, the empty areas (e.g., those areas including no codes) are represented on a display as a grey or grayscale. This shows that no encoded signal (or an encoded signal with a low signal strength as discussed above in Sections II and III) was found in the respective image areas. Additionally, the robustness maps discussed above can be combined with a conflict display map. This will provide a complete picture for a printer or designer, e.g., showing robustness levels (perhaps with swipe information) and any code conflicts.

Graphical text boxes (and corresponding different colors) 27 can be provided by Display Module 506, or included as part of a conflict map, for display on a display screen. For example, the UPC and ES4 codes are shown in yellow since they have matching codes, while the ES3 and the QR codes are shown in different colors since they both conflict with the 1D barcode's code and with each other.

FIG. 20B can be viewed as a conflict map or information supporting a conflict map. The map may reveal information about conflicting separations. For example, the ES3 code corresponds spatially with the castle and sundial in FIG. 20A. This may give a proofer or printer an idea of where the conflict originated. For example, the Valiant Heavy-Duty Hand Soap may belong to a family of soaps, each of which includes the castle and sundial in the design. The different code (ES3) may have resulted since the castle and sundial were pulled from a different family member and used in this case. Thus, a conflict map may be used to find origins of conflicting codes.

Of course, the functionality of the various modules in FIGS. 21A and 21B can be combined into one or more modules, including one or more sub-modules. For example, the Comparator Module 504 and the Results Module 506 can be combined into a single module, as can the Barcode Module 501, Decoder Module 502 and Comparator module 504.

V. Evaluating Encoded Imagery at Predetermined Validation Points to Detect Code Conflicts, and Fidelity Point Selection and Confirmation

Now let's consider spot checking printed press sheets or other printed objects to see if they have any mismatching codes. We use the term “spot checking” to mean that not all of an image, press proof sheet or package (collectively and/or individually referred to as “artwork”) is analyzed to detect code conflicts and/or to determine signal robustness. That is, a subset of the artwork is checked for code conflicts and/or robustness. But we want to ensure that no color channel goes unexamined. So, we preferably look at enough artwork areas to represent all color channels used for a design. That way, a reused or misused printing plate or design file (one with an unintended product identifier) will be detected.

FIG. 22 shows a print layout of packaging or artwork for Cilantro Lime Rice. The package when printed will include six (6) colors: 1. Cyan, 2. Magenta, 3. Yellow, 4. Black, 5. PANTONE 2269C, and 6. PANTONE 402C. The illustrated check sheet shows areas marked with circled, color coded numbers 1-6. These indicate design areas needing to be scanned and analyzed to ensure that there is not a printing plate or design file mismatch. We call these areas “validation points”. The illustrated check sheet can be presented to a presswoman so that she will have a reference point to check a proof sheet pulled from a print run. She scans the proof sheet at a location corresponding to each of the numbered areas (or validation points) on the check sheet, e.g., with a mobile reader or flatbed scanner, to see if an identifier decoded from that area matches the intended identifier. The intended identifier can be obtained from the 1D barcode or otherwise associated with the print run. If the six (6) areas on the print sheet include the same identifier or otherwise correspond to the intended identifier, the print sheet passes the check.

But how do we determine where validation points should be located so that we can create print check sheets, e.g., such as the one illustrated in FIG. 22, or a GUI to guide verification? A detailed description is provided herein with reference to FIGS. 23A, 23B and 23C.

As a general overview, potential validation points can be identified and centered at or around an encoding area. One example of an encoding area may include a so-called digital watermark “tile.” An encoding refresher is helpful here.

In an exemplary system, an encoded payload can be formatted into a binary sequence, which can be encoded and mapped to the locations of a “tile”. For illustration, we describe an implementation of an I by J array of bit cells. The parameters, I and J are positive integers, and the tile can be comprised of an I by I array of bit cells. The size of the tile is configurable and depends on application requirements, such as payload capacity per unit area, robustness, and visibility. Payload capacity increases per unit area with the increase in bit cells per unit area. This additional capacity may be used to improve robustness by redundantly encoding the payload in plural bit cells. Visibility tends to decrease with higher spatial resolution (higher cells per inch (CPI)), as the Human Visual System (HVS) is less sensitive to changes at higher spatial frequencies. Examples of bit cell array sizes include 64 by 64, 128 by 128, 256 by 256 and 512 by 512. While each of these is square and has a dimension that is power of 2, the tile need not be so limited. For example, the tile may have another rectangular form. The bit cells correspond to spatial locations within a tile. In particular, the spatial locations correspond to pixel samples at a configurable spatial resolution, such as 75-600 DPI. The payload can be repeated in contiguous tiles of artwork. An instance of the payload can be encoded in each tile, occupying a block of artwork having a size that depends on the number of bit cells per tile and the spatial resolution. The tile can be redundantly encoded in several contiguous tiles, providing added robustness, as the detector accumulates signal estimates for a payload across tiles. Additionally, the entire payload may be extracted from a portion of a tile in configurations where it is redundantly encoded in sub-tile regions.

A few examples will help illustrate the parameters of a tile. The spatial resolution of the bit cells in a tile may be expressed in terms of cells per inch (CPI). This notation provides a convenient way to relate the bit cells spatially to pixels in an image, which are typically expressed in terms of dots per inch (DPI). Take for example a bit cell resolution of 75 CPI. When a tile is encoded into an image with a pixel resolution of 300 DPI, each bit cell may correspond to a 4 by 4 array of pixels in the 300 DPI image. As another example, each bit cell at 150 CPI corresponds to a region of 2 by 2 pixels within a 300 DPI image, or a region of 4 by 4 pixels within a 600 DPI image. Now, considering tile size in terms of I by J bit cells and setting the size of a bit cell, we can express the tile size by multiplying the bit cell dimension by the number of bit cells per horizontal and vertical dimension of the tile. A tile with 128 by 128 bit cells is about 1.7 by 1.7 inches at a CPI of 75 and about 0.85 by 0.85 inches at a CPI of 150. Each provides the same number of embedding locations per tile (16,384), but occupies a different spatial area based on the spatial resolution the two-dimensional array of bit cells. At each of these 16,384 tiny regions, the luminance of the artwork is subtly increased or decreased to thereby encode a plural bit (e.g., 64-bit) payload.

One particular method of encoding a plural-bit watermark payload in imagery of host artwork begins by error-correction coding the payload to yield a large set of raw bits. (Techniques such as block codes, BCH, Reed Solomon, convolutional codes, and turbo codes may be used.) These raw bits are XORed with a pseudo-random noise sequence. Each result is spatially mapped to plural of the 16,384 different regions and serves to tweak its luminance. The magnitudes of the tweaks may be adjusted, at different locations, in accordance with a model of human visual perception—as applied to the host artwork at the locations where the tweak values will be applied. The tweak values are then summed with the pixel values of the host artwork. Many digital watermarks also convey a calibration signal. This signal (which can comprise a known signal in a transform domain, such as a sparse array of peaks (e.g., 30 to 120 peaks, and preferably 50-70) in the Fourier magnitude domain) enables a watermark detector to discern how an image submitted for decoding has been geometrically transformed since it was originally encoded. For example, the calibration signal (which may be also called an orientation signal or reference signal) allows the detector to discern an amount by which the image has been shifted in X- and Y-directions (translation), an amount by which it has been changed in scale, and an amount by which it has been rotated. With knowledge of such “pose” information (geometric state information), the watermark detector can compensate for, e.g., counter-distort, the geometrical distortion of the image since its original watermarking and can correctly extract the watermark payload. Example of orientation signals are provided, e.g., in assignee's U.S. Pat. Nos. 9,842,163, 9,747,656, 7,986,807, 7,046,819, 6,614,914, 6,625,297, which are each incorporated herein by reference in its entirety.

Phew!

So, let's move onto FIG. 23A and discuss choosing spatial image locations for validation points.

Two grayscale images are created for each color channel in an artwork design. This act produces, for each color channel in a design, one grayscale image for the color channel and one grayscale image for an inverted version of the color channel. So, if doing this for the FIG. 22 design, 12 grayscale images would be produced, two grayscale images for each of the six color channels. A virtual grid is established over each of the grayscale images. Grid points can be positioned n pixels apart, where n is a positive integer. For example, the points can be, e.g., 12, 24, 48, 64, 128 or 256 pixels apart. We currently prefer distancing the points 64 pixels apart. Virtual grid points are illustrated as red points in FIGS. 24A-24D. (Of course, in practice, grid points need not be visually produced and are provided here in the figures for illustration purposes.)

A signal detector operates on image blocks centered at each of the virtual grid points. These points might not correspond to the center of an actual embedding tile and, in practice, rarely do. The detector can be configured to output detection information or measures, e.g., such as is discussed in Sections I and II., above. For example, the detector can determine areas likely to include a detectable signal by locating information suggesting the initial detection of a portion of the data signal used for synchronization. This may indicate presence of a candidate data signal. Such areas indicating candidate data signal(s) are maintained while other grid locations are removed. Virtual grid points not including a likely detectable signal can be removed. This process may or may not include a so-called “full decode,” in which the detector successfully decodes a plural-bit message signal.

It is determined which corresponding grayscale images (inverted and non-inverted) for each color channel include embedded signals. Possible outcomes are “None,” “Non-inverted,” “Inverted,” and “Both”. No validation points are selected for a color channel in which neither the inverted nor the non-inverted grayscale includes a detectable signal. Also, if both the inverted and non-inverted channels include a likely detectable signal, a report can be issued indicating a possible embedding error within that color channel, since a channel will typically not include both.

A center of a tile is located for each remaining grid point. For example, as discussed above in Section I., a synchronizer module 246 may synchronize image data to enable data extraction. Synchronizing may include, for example, determining the distortion to the host signal and compensating for it. This process provides the location and arrangement of encoded data elements within the host signal. A data extractor module 248 obtains this location and arrangement and the corresponding protocol and demodulates a data signal from the host. The location and arrangement provide the locations of encoded data elements. An initial synchronization can provide synchronization parameters that enable the data extractor to apply extraction filters at the correct orientation, scale and location of a tile. These centers are shown with a green “x” in FIGS. 24A-24C. The signal detector is operated on tiles centered at the newly located centers (green x's). Detectability measures can be determined for each of the remaining tiles. For example, as discussed above in Section II., a message strength (MS) and/or Linear Reference Pattern Strength (LRPS) can be determined for each tile. A tile with the largest measure (or combined measures) is used as a validation point for that color channel. Such tiles are shown with a yellow circle in FIGS. 24A-24C. So, the circled numbers 1-6 in the FIG. 22 check sheet correspond to a tile having the largest detectability measure(s). These areas can be determined following an embedding stage, and a check sheet can be produced at that time. Of course, the check sheet need not be printed, and can be stored along with the digital design which a presswoman may access over a network (or local cache).

Different versions of the FIG. 23A flow can be alternatively employed.

For example, instead of using a virtual grid as a starting point, a detector may try to obtain detectability measures from an image reference point, e.g., top left corner of the artwork or a center point of the image. Data blocks can be established from such an image reference point. Sliding windows and overlapping windows can also identify image blocks to search for encoded data.

Also, as shown in FIG. 23B, a signal detector can scan each color channel of a design to locate areas, e.g., blocks or tiles, likely including an encoded signal. The FIG. 23A flow diagram would invert each color channel by generating an inverse grayscale image for each color channel. This is helpful to identify encoding that may be inversely relative to a baseline encoding scheme. For example, a baseline encoding technique may use positive signal contrast to indicate presence of a signal element. When dealing with dark colors, however, holes may be created in the dark color, and then filled in with a lighter color. This lower signal carrier to color contrast could yield an inverted signal. See, e.g., assignee's U.S. Pat. No. 10,580,103, including its discussion of holes and inverted sparse mark signals. The U.S. Pat. No. 10,580,103 patent is hereby incorporated herein by reference in its entirety including all drawings and any appendices. So, checking for an inverted signal (e.g., generating and analyzing an inverse grayscale) makes sense if such inverted encoding techniques could be used in an overall embedding platform. Of course, if such inverted encoding techniques are not present within the embedding environment, an inverse greyscale need not be generated, as shown in FIG. 23B.

Detectability measures can be generated once tile centers are located. A tile having the strongest detectability measure(s) is identified as a Validation Point for that color channel. Each color channel included in a design is processed accordingly to find a tile having the strongest detectability measure(s). A check sheet, e.g., as shown in FIG. 22, is generated showing spatial locations to check for code conflicts based on the determined Validation Points.

Another embodiment, with reference to FIG. 23C, handles a scenario in which a full decode is preferred when determining validation points, but may not be achieved after running a detector on titles centered on a determined center. So, after the 2^(nd) to last stage in FIG. 23A (“run detector on tiles at determined center, generate detectability measures”), a determination is made whether the detector is able to achieve a full message decode, e.g., successfully obtain a payload from a signal centered at a predetermined center. This alternative embodiment is helpful in cases where distortion may be added to encoded artwork to model, e.g., printing and scanning. The distortion may render a candidate tile undecodable. If one or more full decodes occurs at this process point, then a centered point with a maximum detection measure is reported out to be used as a validation point. FIG. 26A shows this case, where red dots represent the virtual grid points, yellow “x's” represent determined tile centers, the green “x” represents a determined tile with a successful full decode, and the blue circle represents the tile with the highest detection measures that is selected as a validation point.

If no full decode occur, however, the process returns to analyze detection results based on remaining detector blocks centered on virtual grid points. If one or more a full decodes occurred at or around virtual grid points, then a virtual grid point with a maximum detection measure is reported out to be used as a validation point. FIG. 26B shows this case, where red dots represent the virtual grid points, yellow “x's” represent determined tile centers, and the blue circle represents the virtual grid point with the highest detection measures that is selected as a validation point. Note here, unlike FIG. 26A, there are no green “x's”, indicating that there are no full decodes from detection blocks centered at determined centers.

A handheld verification tool is now discussed with reference to FIGS. 25A-25H. From a presswoman's perspective, a Verifier App is launched (FIG. 25A) on a mobile device such as an iPhone Xs or XR or Android device such as a Pixel 3 or Samsung Galaxy. The App's splash screen (or, alternatively, a help screen) is shown in FIG. 25A. The presswoman will analyze a proof sheet pulled from a press run, including scanning the proof sheet at spatial locations associated with validation points (see, e.g., FIG. 22). The presswoman enters a project code into the App that is associated with the proof sheet, or a 1D or 2D barcode on the proof sheet is scanned with a camera carried by the mobile device (FIG. 25B-25D). Identifiers (e.g., GTINs) are obtained. The App itself may generate a graphic overlay corresponding to previously identified validation points (e.g., identified at embedding time). In some embodiments the App accesses a digital version of the check sheet, or a spatial location for each validation point. A graphic overlay generated by the App guides the presswoman to each of the validation points, and prompts image capture by launching or activating the camera once the view screen is located at or around a validation point. The App may also use image feature tracking, e.g., as taught in our U.S. Pat. No. 9,684,941, which is hereby incorporated herein by reference in its entirety, to help guide a user to the next validation point. The App (or a detector in communication with the App) decodes the encoded signals from each validation point area and checks a decoded message against an expected identifier. The App displays a “pass” or “fail” or color warning (e.g., red for fail or code conflict (FIG. 25F), and green for pass (FIG. 25E)) to alert the presswoman to any potential problems with the proof sheet. FIG. 25E also shows a signal coverage of an encoded signal with a green overlay for successful reads and code matches, with FIG. 25F showing the spatial area of code mismatches in red. The App may also prompt the presswoman to check for an additional area if a Validation Point is missed or overlooked, e.g., based on a template associated with the GTIN. In other cases, the App may not give a code conflict check if one or more of the validation points is skipped. Results of this validation process, e.g., scanning each of the validation point areas and comparing against an expected identifier, can be recorded in the App and stored in a history log, and/or communicated back to a designer or product owner as proof of code integrity between channels. See FIGS. 25G and 25H, and FIG. 25A.

Another technology, utilizing so-called Fidelity Points, is helpful to identify whether a package is printed with sufficient robustness or encoding strength. Printers desire to know whether they have printed an encoded package correctly, so that the package scans (e.g., successfully decodes encoded signals) according to customer expectations at Point of Sale (POS) locations. Printers are familiar with an A-F grading system for 1D barcodes and desire something similar for other encoded signals, e.g., watermarks. Fidelity Points are designed to provide a print Quality Control (QC) solution to determine whether a press has successfully reproduced an encoded signal from a digital artwork design, and alert printers when there has been significant degradation of the encoded signal during printing. The term “significant” here indicates a potential non-detect situation. Consider the following definitions and descriptions to aid discussion.

Fidelity Points—Image areas that are selected to confirm whether an encoded design is printed with enough signal robustness so as to allow detection of its encoded signal. These areas are selected in the digital realm and then corresponding areas on a printed version are checked to determine robustness. In one example, Fidelity Points include a set of encoding block (e.g., “tile”) centers whose digital robustness and print-copy robustness can be compared, thus providing a monitoring solution for a printed encoded signal at press. Detectability measure(s) can be used as a robustness indicator. Detectability measures can be determined from a digital design, while print-copy detectability measures can be determined from an optical image representing a printed package (or other printed object, e.g., label or hang tag). In some embodiments, the set will include at least one tile member for each type of encoding technique used in a design. In other embodiments, only a predetermined number of Fidelity Points are selected regardless of the number of encoding techniques in a design.

Fidelity Point Selection—This represents a process to select image areas to monitor for robustness. In one example, and from an encoded digital design, a set of encoded signal block (or tile) centers are selected, and their corresponding detectability measure(s) are determined. Detectability measures can be determined, for example, as discussed above in Section II., including determining a message strength (MS) and/or Linear Reference Pattern Strength (LRPS).

Fidelity Point Confirmation—Confirm whether selected Fidelity Points achieve a predetermined detectability measure from a captured image. For example, a full color or RGB scan (e.g., using an EPSON V39 scanner) of a print sample is captured. At determined locations corresponding to the selected Fidelity Points, corresponding detectability measure(s) are extracted and evaluated to see if they have significantly degraded. “Significant degradation” is defined as when a given Fidelity Point's detectability measure (e.g., a probability between 1 and 0, or 100 and 0) drops from ≥80 (or 0.8) in a digital design, to ≤30 (or 0.3) in an evaluation of a print sample. In another embodiment, a significant degradation occurs when a given Fidelity Point's detectability measure (e.g., a probability between 1 and 0, or 100 and 0) drops from ≥70 (or 0.7) in a digital design, to ≤25 (or 0.25) in an evaluation of a print sample. In still another embodiment, a significant degradation occurs when a given Fidelity Point's detectability measure (e.g., a probability between 1 and 0, or 100 and 0) drops from ≥60 (or 0.6) in a digital design, to ≤20 (or 0.20) in an evaluation of a print sample. Confirmation hopefully reveals that an encoded printed design has not significantly degraded.

Consider the following algorithms for Fidelity Point Selection:

-   -   1. Obtain a digital artwork file (also referred to as a digital         design or digital artwork) including one or more encoded signals         therein. The digital artwork file may include multiple instances         of an encoded signal, e.g., tiled across an image or image area,         and/or across multiple different color channels.     -   2. From the encoded digital artwork file, select a set of block         or tile centers, and extract or determine their corresponding         detectability measures. For example, a probability corresponding         to a combination of MS and LRPS can be used.     -   3. Group or “bin” tiles having the same encoding technology. For         example, tiles encoded with a “sparse mark” are grouped in a         first bin (see, e.g., U.S. Pat. No. 9,635,378, US Published         Patent Application No. US 2019-0332840 A1, and International         application no. PCT/US19/19410 (published as WO2019165364),         filed Feb. 25, 2019, each of which are hereby incorporated         herein by reference in its entirety), while tiles with spot         color encoding are grouped in a second bin (see, e.g., U.S. Pat.         Nos. 9,380,186 and 10,270,936, which are each hereby         incorporated herein by reference in its entirety), and while         encoding using CMY and/or K are grouped in a third bin (see,         e.g., U.S. Pat. Nos. 9,380,186, 10,032,241, and 6,891,959, which         are each hereby incorporated herein by reference in its         entirety). The bins can be optionally refined further to         represent different overprinting, colors, and/or tones. For         example, “CMY encoding without K overprinting” and “CMY encoding         with K overprinting” can be viewed as different encoding         technologies.     -   4. For each bin, remove any tiles having a detectability measure         below a predetermined threshold. For example, tiles having a         detectability measure probability, representing a message         strength and an orientation component strength, less than or         equal to 0.79, or less than or equal to 0.69, or less than or         equal to 0.59, are discarded. If a bin does not have any         qualified tiles relative to the threshold, processing moves onto         the next bin.     -   5. Within each bin, if multiple tiles remain, selection priority         can be determined based on location. For example, tiles         surrounded by peer tiles having the same type of encoding         technology are prioritized higher than those without neighbors,         or with fewer such neighbors. In another example, a tile that is         centrally located within an image is prioritized over tiles         located closer to package edges. If there are multiple tiles         with the same neighbor weight (e.g., same number of neighbors),         select the one with a lower detectability measure. While we         preferably selected only 1 tile per bin as a Fidelity Point, we         can optionally select up to 5 tiles per bin. Alternatively, a         total number of Fidelity Points is selected across all bins,         e.g., only 3-11 bins despite the number of bins, and Fidelity         Point Selection stops once the total number is reached. In one         example, 17 bins (or other number) are determined; yet, only 2-7         total Fidelity Points are allowed. A prioritization methodology         to select the 2-7 total Fidelity Points is discussed below.     -   6. Spatially locate Selected Fidelity Points relative to the         encoded digital artwork. These spatial locations can be used to         generate a press check sheet, which highlights Fidelity Point         locations to be scanned by a mobile device, handheld scanner,         inline scanner (e.g., on press scanner) or flatbed scanner.

Bin Prioritization Algorithms

1. Optionally, prioritize bins based on ink color. For example, if embedding background or white areas with so-called Digimarc Light inks (see, e.g., U.S. Pat. No. 10,445,849, which is hereby incorporated herein by reference in its entirety), related bins can be moved to the top of the list for processing. Bins associated with inks designated as important or otherwise likely to include encoding can be optionally prioritized highly.

2. Sort bins based on their tile counts in descending order. For example, with reference to FIGS. 27A and 27C, four embedding techniques are used for a package design. These different encoding techniques are represented by different colors: blue, orange, yellow and purple. Blue has 9 tiles (B1-B9), orange 6 tiles (OR1-OR6), yellow has 3 tiles (Y1-Y3) and purple 2 has tiles (P1&P2). So, they are ordered in descending order: blue, orange, yellow, purple.

3. Introduce a weighting factor to “discount” a bin's tile count that has the same encoding or modulating ink that is used in a previous bin, to give a low-tile-count-but-unique-modulating-ink bin a better chance at selecting a Fidelity Point therefrom. And then sort the bins again based on the updated tile counts. In the FIGS. 27A and 27C example, Black ink is used to carry an encoded signal in blue, orange and yellow, and Cyan is used to carry an encoded signal in yellow. If the discount factor is ½ (or other number), orange is reduced to 3 since it has the same modulating ink as blue, and yellow is reduced to 1.5 for the same reason. This allows the purple tile bin to be prioritized above the yellow tile bin in this example.

4. If two or more bins have the same tile counts, use averaged detectability measures of qualified tiles from each bin to break the tie, and prioritize the one with the larger average above the ones with a smaller average.

5. Scan through the bin list selecting 1 Fidelity Point per bin until x Fidelity Points are selected (e.g., x=2-9 tiles), or until y % image area coverage is reached (e.g., y=60%-100% image area coverage, preferably at least 80%). For the image area coverage, and with reference to FIG. 27A, 3 Fidelity Points are selected, one blue tile B5 (representing 9 tiles), one orange tile OR3 (representing 6 tiles) and one purple tile P1 (representing 2 tiles). This selection represents a coverage area of 17 tiles/27 total image tiles (total includes 7 tiles without signal), or 63%. FIG. 27B shows a heat map of the FIG. 27A encoded image, with white representing image area with encoding and black representing image areas without encoding (or with low detectability). The total image area coverage can be alternatively calculated by viewing coverage of available encoded tiles. So, with reference to FIG. 27A, the total image area coverage would be 17/20 tiles, or 85%. The selection process can repeat again through the bins if more Fidelity Points are allowed to be selected. (Alternatively, selection ends after all bins are evaluated or after zero Fidelity Points are determined.)

Tile Prioritization Algorithms:

1. For each bin in the sorted order, discard tiles whose detectability measures fall below a threshold. For example, discard those tiles falling below, 80%, 70% or 60%. Then sort remaining bin tiles by neighbor count in descending order. For example, with reference to FIG. 27A, blue tiles B1, B6 and B7 each have zero (0) neighbors encoded with the same encoding technique. Tile B2 has 3 neighbors encoded with the same embedding technique, B3, B4 and B5. B5 has the most blue neighbors encoded with the same encoding technique, B2, B3, B4, B8 and B9. So B5 would be prioritized first in the blue bin, with B1, B6 and B7 tied for last. For orange tiles, OR3 has the most similarly encoded neighbors, OR1, OR2, OR4, OR5 and OR6. So, it would be the highest prioritized tile in the orange bin. P1 and P2 are both tied at zero neighbors each. The tile with the most neighbors can be selected as that bin's Fidelity Point. If there is a tie, e.g., as is the case with the purple bins in FIG. 27A:

-   -   a. Sort by tile's detectability measure(s) strength or         probability. The lowest score is preferably chosen since it         represents the most likely to fail case. Otherwise, the         strongest tile is selected.     -   b. If the tie persists, then sort by image location, e.g., top         to bottom, left-to-right, or a random selection of tied tiles         can be made.         Alternatively, a tile can be higher prioritized if it also         corresponds with a Validation Point (as discussed above).

2. Optionally, for so-call dual-bins, e.g., bins representing tiles that have more than one modulating ink, no Fidelity Point is selected from such a bin. However, a dual-bin tile can be considered for a Fidelity Point candidate if no single-bin tiles can be found for that encoding technique bin.

3. For each bin, if it does not have any tile meeting the detectability measure (e.g., all tiles in this bin have detectability measures, e.g., <70%), move to the next bin.

Sometimes we find encoded designs with overlapping tiles. This may occur, e.g., when image elements or layers are combined or encoded separately. Selecting a tile as Fidelity Point, when that tile has an overlapping tile, may cause confusion on what tile center should be used when calculating detectability measures. So, to avoid any confusion, overlapping tiles are preferably not considered in the Fidelity Point Selection process. Additionally, overlapping or misaligned tiles are not be counted as a neighbor. However, a design can still allow an overlapping tile to be counted towards a bin's total tile count, regardless of overlapping.

Fidelity Point Confirmation

Once a package has been printed with an encoded signal, Fidelity Point Confirmation can be carried out to see if the encoded signal has significantly degraded, or whether the encoded signal remains detectable. In one embodiment, an RGB scan (e.g., using an EPSON V39 scanner) of a printed sample is taken. The red channel is evaluated since this is the channel that most closely resembles a red-LED scanner. From this scan, detectability measures are determined at locations corresponding to previously selected Fidelity Points. To avoid false alarm (e.g., where an otherwise good print sample is falsely labeled “bad”), a Fidelity Point Confirmation failure is only declared when a significant degradation in robustness is observed. For example, if the detectability measures in the printed objects fall below a predetermined probability, e.g., less than 40%-20%, preferably is less than 30%, significant degradation is determined.

Another Fidelity Point Selection embodiment is discussed with reference to FIG. 28. Encoding techniques are identified in a design file, including, e.g., whether different inks, tones, overprints are used. A unique bin is created for each encoding technique. Encoded tiles (or Fidelity Point Candidates (FPCs)) are added to bins, and a tile count is maintained. Encoded tiles that do not meet predetermined detectability measures are excluded from the bin, and the tile count is corrected, if needed. A Fidelity Point for each bin is selected based, e.g., on neighborhood count, detectability measure strength, and/or image location. Alternatively, a predetermined number of Fidelity Points are selected from ordered bins regards of the number of bins. The corresponding Fidelity Point's image location is stored for use when a printed version is tested.

VI. Operating Environments

The components and operations of the various described embodiments can be implemented in modules. Notwithstanding any specific discussion of the embodiments set forth herein, the term “module” may refer to software, firmware and/or circuitry configured to perform any of the methods, processes, functions or operations described herein. Software may be embodied as a software package, code, instructions, instruction sets, or data recorded on non-transitory computer readable storage mediums. Software instructions for implementing the detailed functionality can be authored by artisans without undue experimentation from the descriptions provided herein, e.g., written in C, C++, MatLab, Visual Basic, Java, Python, Tcl, Perl, Scheme, Ruby, and assembled in executable binary files, etc., in conjunction with associated data. Firmware may be embodied as code, instructions or instruction sets or data that are hard-coded (e.g., nonvolatile) in memory devices. As used herein, the term “circuitry” may include, for example, singly or in any combination, hardwired circuitry, programmable circuitry such as one or more computer processors comprising one or more individual instruction processing cores, parallel processors, state machine circuitry, or firmware that stores instructions executed by programmable circuitry.

Applicant's work also includes taking the scientific principles and natural laws on which the present technology rests and tying them down in particularly defined implementations. One such implementation is electronic circuitry that has been custom-designed and manufactured to perform some or all of the component acts, as an application specific integrated circuit (ASIC).

To realize such an implementation, some or all of the technology is first implemented using a general-purpose computer, using software such as MatLab (from Mathworks, Inc.). A tool such as HDLCoder (also available from MathWorks) is next employed to convert the MatLab model to VHDL (an IEEE standard, and doubtless the most common hardware design language). The VHDL output is then applied to a hardware synthesis program, such as Design Compiler by Synopsis, HDL Designer by Mentor Graphics, or Encounter RTL Compiler by Cadence Design Systems. The hardware synthesis program provides output data specifying a particular array of electronic logic gates that will realize the technology in hardware form, as a special-purpose machine dedicated to such purpose. This output data is then provided to a semiconductor fabrication contractor, which uses it to produce the customized silicon part. (Suitable contractors include TSMC, Global Foundries, and ON Semiconductors.)

Another specific implementation of the present disclosure includes barcode and/or encoded signal detection operating on a specifically configured smartphone (e.g., iPhone 6 or Android device) or other mobile device, such phone or device. The smartphone or mobile device may be configured and controlled by software (e.g., an App or operating system) resident on the smartphone device. The resident software may include, e.g., a barcode decoder, digital watermark detector and detectability measure generator module.

For the sake of further illustration, FIG. 8 is a diagram of an electronic device (e.g., a smartphone, mobile device, tablet, laptop, or other electronic device) in which the components of the above encoder, decoder, and various Module embodiments may be implemented. It is not intended to be limiting, as the embodiments may be implemented in other device architectures or electronic circuitry.

Referring to FIG. 8, a system for an electronic device includes bus 100, to which many devices, modules, etc., (each of which may be generically referred as a “component”) are communicatively coupled. The bus 100 may combine the functionality of a direct memory access (DMA) bus and a programmed input/output (PIO) bus. In other words, the bus 100 may facilitate both DMA transfers and direct CPU read and write instructions. In one embodiment, the bus 100 is one of the Advanced Microcontroller Bus Architecture (AMBA) compliant data buses. Although FIG. 8 illustrates an embodiment in which all components are communicatively coupled to the bus 100, it will be appreciated that one or more sub-sets of the components may be communicatively coupled to a separate bus in any suitable or beneficial manner, and that any component may be communicatively coupled to two or more buses in any suitable or beneficial manner. Although not illustrated, the electronic device can optionally include one or more bus controllers (e.g., a DMA controller, an I2C bus controller, or the like or any combination thereof), through which data can be routed between certain of the components.

The electronic device also includes a CPU 102. The CPU 102 may be any microprocessor, multi-core microprocessor, parallel processors, mobile application processor, etc., known in the art (e.g., a Reduced Instruction Set Computer (RISC) from ARM Limited, the Krait CPU product-family, any X86-based microprocessor available from the Intel Corporation including those in the Pentium, Xeon, Itanium, Celeron, Atom, Core i-series product families, etc.). Another CPU example is an Apple A8 or A7. The A8 is built on a 64-bit architecture, includes a motion co-processor and is manufactured on a 20 nm process. The CPU 102 runs an operating system of the electronic device, runs application programs (e.g., mobile apps such as those available through application distribution platforms such as the Apple App Store, Google Play, etc., or custom designed to include watermark detection and object authentication) and, optionally, manages the various functions of the electronic device. The CPU 102 may include or be coupled to a read-only memory (ROM) (not shown), which may hold an operating system (e.g., a “high-level” operating system, a “real-time” operating system, a mobile operating system, or the like or any combination thereof) or other device firmware that runs on the electronic device. Watermark detection capabilities can be integrated into the operating system itself.

The electronic device may also include a volatile memory 104 electrically coupled to bus 100. The volatile memory 104 may include, for example, any type of random access memory (RAM). Although not shown, the electronic device may further include a memory controller that controls the flow of data to and from the volatile memory 104.

The electronic device may also include a storage memory 106 connected to the bus. The storage memory 106 typically includes one or more non-volatile semiconductor memory devices such as ROM, EPROM and EEPROM, NOR or NAND flash memory, or the like or any combination thereof, and may also include any kind of electronic storage device, such as, for example, magnetic or optical disks. In embodiments of the present invention, the storage memory 106 is used to store one or more items of software. Software can include system software, application software, middleware (e.g., Data Distribution Service (DDS) for Real Time Systems, MER, etc.), one or more computer files (e.g., one or more data files, configuration files, library files, archive files, etc.), one or more software components, or the like or any stack or other combination thereof. Examples of system software include operating systems (e.g., including one or more high-level operating systems, real-time operating systems, mobile operating systems, or the like or any combination thereof), one or more kernels, one or more device drivers, firmware, one or more utility programs (e.g., that help to analyze, configure, optimize, maintain, etc., one or more components of the electronic device), and the like.

Application software typically includes any application program that helps users solve problems, perform tasks, render media content, retrieve (or access, present, traverse, query, create, organize, etc.) information or information resources on a network (e.g., the World Wide Web), a web server, a file system, a database, etc. Examples of software components include device drivers, software CODECs, message queues or mailboxes, databases, etc. A software component can also include any other data or parameter to be provided to application software, a web application, or the like or any combination thereof. Examples of data files include image files, text files, audio files, video files, haptic signature files, and the like.

Also connected to the bus 100 is a user interface module 108. The user interface module 108 is configured to facilitate user control of the electronic device. Thus, the user interface module 108 may be communicatively coupled to one or more user input devices 110. A user input device 110 can, for example, include a button, knob, touch screen, trackball, mouse, microphone (e.g., an electret microphone, a MEMS microphone, or the like or any combination thereof), an IR or ultrasound-emitting stylus, an ultrasound emitter (e.g., to detect user gestures, etc.), one or more structured light emitters (e.g., to project structured IR light to detect user gestures, etc.), one or more ultrasonic transducers, or the like or any combination thereof.

The user interface module 108 may also be configured to indicate, to the user, the effect of the user's control of the electronic device, or any other information related to an operation being performed by the electronic device or function otherwise supported by the electronic device. Thus, the user interface module 108 may also be communicatively coupled to one or more user output devices 112. A user output device 112 can, for example, include a display (e.g., a liquid crystal display (LCD), a light emitting diode (LED) display, an active-matrix organic light-emitting diode (AMOLED) display, an e-ink display, etc.), a light, an illumination source such as a flash or torch, a buzzer, a haptic actuator, a loud speaker, or the like or any combination thereof. In the case of an iPhone 6, the flash includes a True Tone flash including a dual-color or dual-temperature flash that has each color firing at varying intensities based on a scene to make sure colors and skin tone stay true.

Generally, the user input devices 110 and user output devices 112 are an integral part of the electronic device; however, in alternate embodiments, any user input device 110 (e.g., a microphone, etc.) or user output device 112 (e.g., a loud speaker, haptic actuator, light, display, or printer) may be a physically separate device that is communicatively coupled to the electronic device (e.g., via a communications module 114). A printer encompasses many different devices for applying our encoded signals to objects, such as 2D and 3D printers, etching, engraving, flexo-printing, offset printing, embossing, laser marking, etc. The printer may also include a digital press such as HP's indigo press. An encoded object may include, e.g., a consumer-packaged product, a label, a sticker, a logo, a driver's license, a passport or other identification document, etc.

Although the user interface module 108 is illustrated as an individual component, it will be appreciated that the user interface module 108 (or portions thereof) may be functionally integrated into one or more other components of the electronic device (e.g., the CPU 102, the sensor interface module 130, etc.).

Also connected to the bus 100 is an image signal processor 116 and a graphics processing unit (GPU) 118. The image signal processor (ISP) 116 is configured to process imagery (including still-frame imagery, video imagery, or the like or any combination thereof) captured by one or more cameras 120, or by any other image sensors, thereby generating image data. General functions typically performed by the ISP 116 can include Bayer transformation, demosaicing, noise reduction, image sharpening, filtering, or the like or any combination thereof. The GPU 118 can be configured to process the image data generated by the ISP 116, thereby generating processed image data. General functions typically performed by the GPU 118 include compressing image data (e.g., into a JPEG format, an MPEG format, or the like or any combination thereof), creating lighting effects, rendering 3D graphics, texture mapping, calculating geometric transformations (e.g., rotation, translation, etc.) into different coordinate systems, etc. and send the compressed video data to other components of the electronic device (e.g., the volatile memory 104) via bus 100. The GPU 118 may also be configured to perform one or more video decompression or decoding processes. Image data generated by the ISP 116 or processed image data generated by the GPU 118 may be accessed by the user interface module 108, where it is converted into one or more suitable signals that may be sent to a user output device 112 such as a display, printer or speaker. GPU 118 may also be configured to serve one or more functions of a watermark detector. In some cases, GPU 118 searches for a watermark orientation component, while payload resolution is performed by the CPU 102.

Also coupled the bus 100 is an audio I/O module 122, which is configured to encode, decode and route data to and from one or more microphone(s) 124 (any of which may be considered a user input device 110) and loudspeaker(s) 126 (any of which may be considered a user output device 110). For example, sound can be present within an ambient, aural environment (e.g., as one or more propagating sound waves) surrounding the electronic device. A sample of such ambient sound can be obtained by sensing the propagating sound wave(s) using one or more microphones 124, and the microphone(s) 124 then convert the sensed sound into one or more corresponding analog audio signals (typically, electrical signals), thereby capturing the sensed sound. The signal(s) generated by the microphone(s) 124 can then be processed by the audio I/O module 122 (e.g., to convert the analog audio signals into digital audio signals) and thereafter output the resultant digital audio signals (e.g., to an audio digital signal processor (DSP) such as audio DSP 128, to another module such as a song recognition module, a speech recognition module, a voice recognition module, etc., to the volatile memory 104, the storage memory 106, or the like or any combination thereof). The audio I/O module 122 can also receive digital audio signals from the audio DSP 128, convert each received digital audio signal into one or more corresponding analog audio signals and send the analog audio signals to one or more loudspeakers 126. In one embodiment, the audio I/O module 122 includes two communication channels (e.g., so that the audio I/O module 122 can transmit generated audio data and receive audio data simultaneously).

The audio DSP 128 performs various processing of digital audio signals generated by the audio I/O module 122, such as compression, decompression, equalization, mixing of audio from different sources, etc., and thereafter output the processed digital audio signals (e.g., to the audio I/O module 122, to another module such as a song recognition module, a speech recognition module, a voice recognition module, etc., to the volatile memory 104, the storage memory 106, or the like or any combination thereof). Generally, the audio DSP 128 may include one or more microprocessors, digital signal processors or other microcontrollers, programmable logic devices, or the like or any combination thereof. The audio DSP 128 may also optionally include cache or other local memory device (e.g., volatile memory, non-volatile memory or a combination thereof), DMA channels, one or more input buffers, one or more output buffers, and any other component facilitating the functions it supports (e.g., as described below). In one embodiment, the audio DSP 128 includes a core processor (e.g., an ARM® AudioDE™ processor, a Hexagon processor (e.g., QDSP6V5A)), as well as a data memory, program memory, DMA channels, one or more input buffers, one or more output buffers, etc. Although the audio I/O module 122 and the audio DSP 128 are illustrated as separate components, it will be appreciated that the audio I/O module 122 and the audio DSP 128 can be functionally integrated together. Further, it will be appreciated that the audio DSP 128 and other components such as the user interface module 108 may be (at least partially) functionally integrated together.

The aforementioned communications module 114 includes circuitry, antennas, sensors, and any other suitable or desired technology that facilitates transmitting or receiving data (e.g., within a network) through one or more wired links (e.g., via Ethernet, USB, FireWire, etc.), or one or more wireless links (e.g., configured according to any standard or otherwise desired or suitable wireless protocols or techniques such as Bluetooth, Bluetooth Low Energy, WiFi, WiMAX, GSM, CDMA, EDGE, cellular 3G or LTE, Li-Fi (e.g., for IR- or visible-light communication), sonic or ultrasonic communication, etc.), or the like or any combination thereof. In one embodiment, the communications module 114 may include one or more microprocessors, digital signal processors or other microcontrollers, programmable logic devices, or the like or any combination thereof. Optionally, the communications module 114 includes cache or other local memory device (e.g., volatile memory, non-volatile memory or a combination thereof), DMA channels, one or more input buffers, one or more output buffers, or the like or any combination thereof. In one embodiment, the communications module 114 includes a baseband processor (e.g., that performs signal processing and implements real-time radio transmission operations for the electronic device).

Also connected to the bus 100 is a sensor interface module 130 communicatively coupled to one or more sensor(s) 132. Sensor 132 can, for example, include an accelerometer (e.g., for sensing acceleration, orientation, vibration, etc.), a magnetometer (e.g., for sensing the direction of a magnetic field), a gyroscope (e.g., for tracking rotation, orientation, or twist), a barometer (e.g., for sensing air pressure, from which relative elevation can be determined), a wind meter, a moisture sensor, an ambient light sensor, an IR or UV sensor or other photodetector, a pressure sensor, a temperature sensor, an acoustic vector sensor (e.g., for sensing particle velocity), a galvanic skin response (GSR) sensor, an ultrasonic sensor, a location sensor (e.g., a GPS receiver module, etc.), a gas or other chemical sensor, or the like or any combination thereof. Although separately illustrated in FIG. 8, any camera 120 or microphone 124 can also be considered a sensor 132. Generally, a sensor 132 generates one or more signals (typically, electrical signals) in the presence of some sort of stimulus (e.g., light, sound, moisture, gravitational field, magnetic field, electric field, etc.), in response to a change in applied stimulus, or the like or any combination thereof. In one embodiment, all sensors 132 coupled to the sensor interface module 130 are an integral part of the electronic device; however, in alternate embodiments, one or more of the sensors may be physically separate devices communicatively coupled to the electronic device (e.g., via the communications module 114). To the extent that any sensor 132 can function to sense user input, then such sensor 132 can also be considered a user input device 110. The sensor interface module 130 is configured to activate, deactivate or otherwise control an operation (e.g., sampling rate, sampling range, etc.) of one or more sensors 132 (e.g., in accordance with instructions stored internally, or externally in volatile memory 104 or storage memory 106, ROM, etc., in accordance with commands issued by one or more components such as the CPU 102, the user interface module 108, the audio DSP 128, the cue detection module 134, or the like or any combination thereof). In one embodiment, sensor interface module 130 can encode, decode, sample, filter or otherwise process signals generated by one or more of the sensors 132. In one example, the sensor interface module 130 can integrate signals generated by multiple sensors 132 and optionally process the integrated signal(s). Signals can be routed from the sensor interface module 130 to one or more of the aforementioned components of the electronic device (e.g., via the bus 100). In another embodiment, however, any signal generated by a sensor 132 can be routed (e.g., to the CPU 102), the before being processed.

Generally, the sensor interface module 130 may include one or more microprocessors, digital signal processors or other microcontrollers, programmable logic devices, or the like or any combination thereof. The sensor interface module 130 may also optionally include cache or other local memory device (e.g., volatile memory, non-volatile memory or a combination thereof), DMA channels, one or more input buffers, one or more output buffers, and any other component facilitating the functions it supports (e.g., as described above). In one embodiment, the sensor interface module 130 may be provided as the “Sensor Core” (Sensors Processor Subsystem (SPS)) from Qualcomm, the “frizz” from Megachips, or the like or any combination thereof. Although the sensor interface module 130 is illustrated as an individual component, it will be appreciated that the sensor interface module 130 (or portions thereof) may be functionally integrated into one or more other components (e.g., the CPU 102, the communications module 114, the audio I/O module 122, the audio DSP 128, the cue detection module 134, or the like or any combination thereof).

CONCLUDING REMARKS

Having described and illustrated the principles of the technology with reference to specific implementations, it will be recognized that the technology can be implemented in many other, different, forms. To provide a comprehensive disclosure without unduly lengthening the specification, applicant hereby incorporates by reference each of the above referenced patent documents in its entirety. Such documents are incorporated in their entireties, including all drawings and appendices, even if cited above in connection with specific of their teachings. These documents disclose technologies and teachings that can be incorporated into the arrangements detailed, and into which the technologies and teachings detailed herein can be incorporated.

The particular combinations of elements and features in the above-detailed embodiments are exemplary only; the interchanging and substitution of these teachings with other teachings in this and the incorporated-by-reference patents are also contemplated.

Many combinations will be evident from the above disclosure. 

What is claimed is:
 1. An image processing method comprising: obtaining an image comprising one or more encoded signals therein; analyzing the image to determine encoding techniques used to encode the one or more encoded signals therein; for each determined encoding technique, grouping associated encoded image areas within a bin associated with that determined encoding technique; selecting at least one encoded image area from each of two (2) or more bins as test image areas, wherein the test image areas are to be used to determine encoded signal robustness for a printed version of the image.
 2. The image processing method of claim 1 further comprising generating a check sheet including markings identifying spatial locations relative to the test image areas.
 3. The image processing method of claim 1 in which the one or more encoded signals each comprises a synchronization component and a message component, in which said selecting selects based on a decision associated with a detectability measure for each encoded image area within a bin, the detectability measure corresponding to the synchronization component and to the message component.
 4. The image processing method of claim 3 in which said selecting prioritizes bins based on a number of encoded image areas within each bin, and then evaluates bins having more encoded image areas before bins with relatively less encoded image areas.
 5. The image processing method of claim 4 in which said selecting selects an encoded image area from within a prioritized bin based on a neighbor count.
 6. The image processing method of claim 4 in which said selecting omits any encoded image area overlapping another encoded image area.
 7. An image processing method for selecting image areas to test for robustness of encoded signals, said method comprising: obtaining digital artwork comprising a plurality of colors, the digital artwork comprising multiple instances of an encoded signal; selecting a set of encoding tiles, and for each encoding tile determining an encoding detectability measure associated therewith; creating a bin for each encoding technology used to encode an instance of the encoded signal; for each bin, removing any encoding tile having a detectability measure below a predetermined threshold; and then for each bin, prioritizing remaining encoding tiles to yield a prioritization per bin; selecting an encoding tile based on the prioritization per bin, and spatially locating the selected encoding tile relative to the digital artwork.
 8. The image processing method of claim 7 in which the prioritizing is based on encoding tile spatial location within the digital artwork.
 9. The image processing method of claim 8 in which an encoding tile that is centrally located within an image is prioritized over encoding tiles located closer to design file edges.
 10. The image processing method of claim 7 in which the prioritizing is based on a number of neighboring encoding tiles having the same type of encoding technology.
 11. The image processing method of claim 10 in which if there are multiple encoding tiles with the same number of neighbors, an encoding tile with a lower detectability measure is prioritized higher than an encoding tile with a relatively higher detectability measure.
 12. The image processing method of claim 7, in which said prioritizing remaining encoding tiles comprises: determining whether the encoded signal is decoded from an encoding tile to obtain a plural-bit message component carried therein; and prioritizing an encoding tile with a decodable plural-bit message component higher relative to an encoding tile with no decodable plural-bit message component.
 13. The image processing method of claim 12 further comprising generating a check sheet including markings identifying spatial locations of selected encoding tiles relative to the digital artwork.
 14. The image processing method of claim 7 in which the encoded signal comprises a synchronization component and a plural-bit message component, in which the detectability measure comprises a a first measure corresponding to the synchronization component, and a second detectability measure corresponding to the plural-bit message component.
 15. The image processing method of claim 7 in which the prioritizing is based on whether the encoding tile is associated with a validation point, which validation point is associated with a plural-bit code conflict check.
 16. An apparatus comprising: an input to obtain an image comprising one or more encoded signals therein; means for determining a number of encoding techniques used to encode the one or more encoded signals within the image; means for grouping associated encoded image areas by determined encoding technique, with a separate bin being associated with each determined encoding technique; means for selecting at least one encoded image area from each of two (2) or more bins as test image areas, wherein the test image areas are to be used to determine encoded signal robustness for a printed version of the image.
 17. The apparatus of claim 16 further comprising means for generating a check sheet including markings identifying spatial locations relative to the test image areas.
 18. The apparatus of claim 16 in which the one or more encoded signals each comprises a synchronization component and a message component, in which said means for selecting selects based on a decision associated with a detectability measure for each encoded image area within a bin, the detectability measure corresponding to the synchronization component and to the message component.
 19. The apparatus of claim 18 in which said means for selecting prioritizes bins based on a number of encoded image areas within each bin, and then evaluates bins having more encoded image areas before bins with relatively less encoded image areas.
 20. The apparatus of claim 16 in which said means for selecting selects an encoded image area from within a prioritized bin based on a neighbor count. 